I played around with the points cost in the Battlespire character creation. My approach was to start with the absolute worst character possible, all stats at 10, all skills at 5, no items or spells, all disadvantages, and to view every improvement as a points cost. This gave me a start of 44,094 points.

Warning - later in the game, you MUST equip some plot related weapons and armor, of indeterminate quality to proceed. The minimal build forbids all weapons and armor. Hopefully Bethesda made an exception to the forbidden items rule for these plot weapons and armor, but I did not test this. Some of the intrinsic classes have certain forbidden types and materials, and if Bethesda didn't make exceptions for these items, then even an intrinsic class could find the game unwinnable when you encounter plot armor that is higher quality than your class allows. For the record, I played the game to the end with all forbidden weapons except long blades and missiles, and no forbidden armor or weapon material (it would be dumb for a melee class to restrict these, I think).

Anyway, with 44,094 points to play around with, this is what everything costs:

Elemental resistance (total cost to raise a resistance from "Critical Weakness")
Immunity - 3200
Resistance - 2400
Normal tolerance - 1600
Low tolerance - 800

There are five elements total. Poison immunity will not protect you from poison status, and magic immunity will not protect you from continuous damage. I do not know if critical weakness or low tolerance mean extra damage or not.

Magic related advantages/disadvantages:
Regenerate SP - 3000 (includes cost of unchecking 'No SP regen')
Spell absorbtion - 2500
3x Magery - 2200
2x Magery - 1500
Uncheck No regen of SP - 1000
1.5x Magery - 700

I haven't played with any of these.

Forbidden materials (total cost to allow)
Allow heavy armor - 2000
Allow medium armor - 1000
Allow light armor - 600

Allow daedric weapons - 2000
Allow orcish weapons - 1600
Allow ebony weapons - 1400
Allow adamantium weapons - 1200
Allow mithril weapons - 1000
Allow dwarven weapons - 800
Allow elven weapons - 600
Allow silver weapons - 400
Allow steel weapons - 200

The item selected determines the HIGHEST QUALITY material you are allowed to equip. In other words, if you have "forbidden material mithril" selected, you CAN equip mithril weapons, but you may not equip anything better. This is a change from Daggerfall, where you could forbid steel for a big points boost and suffer for a bit until you find better stuff than steel.

I never found any orcish, ebony, or adamantium weapons in my playthrough. There was plenty of daedric stuff in levels 6 and 7 though. In fact, I started off with a mithril claymore and mithril long bow, and I didn't find anything better until level 6 where I got a daedric claymore, and level 7 where I got a daedric crossbow.

And again, there will be a point where you must equip plot related weapons and armor. I do not know if forbidden materials affect this, but if they do, then some classes/builds might find their game unwinnable.

Forbidden weapon types:
Allow missile weapons - 1000
Allow long blades - 800
Allow blunt weapons - 600
Allow short blades - 400
Allow axes - 400

I only allowed missile weapons and long blades in my playthrough. I could equip the plot weapons just fine.

Others advantages:
Regenerate Health - 2000
Rapid Healing - 700
Athleticism - 400
Acute Hearing - 200
Adrenaline Rush - 200

Stats (total cost to raise from 10 to this stat level, per stat)
75 - 4744
70 - 4259
65 - 3794
60 - 3350
55 - 2925
50 - 2519
45 - 2134
40 - 1769
35 - 1425
30 - 1100
25 - 794
20 - 509
15 - 244


Wounds (total cost to raise from 50)
200 - 10,576
190 - 9696
180 - 8841
170 - 8011
160 - 7206
150 - 6426
140 - 5671
130 - 4941
120 - 4236
110 - 3556
100 - 2900
90 - 2270
80 - 1665
70 - 1085
60 - 530


Primary skills:
60 - 1390
55 - 1201
50 - 1024
45 - 860
40 - 609
35 - 570
30 - 444
25 - 330
20 - 229
15 - 140
10 - 64

Major skills:
60 - 1572
55 - 1355
50 - 1151
45 - 963
40 - 790
35 - 632
30 - 490
25 - 361
20 - 248
15 - 150
10 - 67

Minor skills:
60 - 1748
55 - 1501
50 - 1272
45 - 1061
40 - 867
35 - 690
30 - 532
25 - 390
20 - 267
15 - 161
10 - 72

Remember, skills can be trained! Stats only improve when you beat a level, and advantages/disadvantages are forever. Weigh the value of these skills accordingly.

Skills at 5% will rise very quickly at first, but will take a long time before they're good. And not all stats have the same training opportunity. Your weapon stats only go up when you're fighting enemies, which is dangerous when the enemy is tougher than a scamp and your skill isn't very good. Missile skill goes up just from firing, but this is a waste of ammo.

However, there is one other reason to put points into these if you don't mind exploiting a bug. You can't train a skill past its governing stat, but you can start off with some. Want to, for instance, have a high Restoration skill without wasting any points on the otherwise useless PER stat? First, make sure you don't have the Restoration skill on your character sheet. Now pick a skill that is greater than 10 (assuming your PER is 10). Change that stat to Restoration. Now you can raise Restoration all the way to 60.

I have. Here are some observations:
Regenerate SP: The rate of regeneration is not affected by your maximum SP or Rapid Healing. Combining this with 3x Magery and high INT gives you a character who has lots of SP and can regenerate it, but regenerating it will take a while.
Spell Absorption: Sometimes, when hit with a hostile spell (doesn't work for your own area at range spells), you will regain SP instead of being affected by it. I haven't played that far, but this might be able to block poison and continuous damage. If your SP is almost full, I suspect that this ability stops working. It seems to work well when combined with critical weaknesses.
3x Magery: One thing I noticed is that crystals do not restore all your SP if your max SP is really high. It seems that only 175 SP are restored (my character has 74 INT and hence 222 SP). Restore Magicka effects (Magicka Reseratus and Potion of Restoration) still seem to restore all SP (restored from 11 to 225 in a test).
No Regen of SP: This disadvantage prevents you from using Restore Magicka effects (tested with Magica Reseratus); the game will display a message like "you are unable to regenerate spell points this way" and will not let you use it.

Here is my theory about how resistance works in the DOS TES games (Arena, Daggerfall, and Battlespire):

Normally, when hit by an attack spell, you get a saving throw against the spell. modified by your WIL stat. On a successful save, you take half damage; on a failed save, you take full damage.

Of course, the resistance advantages/disadvantages change the way it works. Here are what I believe to be the effects of the resistance traits:
Resistance: On a successful save, you take no damage.
Immunity: You take no damage, no save needed.
Low tolerance: You get a penalty to your saving throw.
Critical weakness: You don't get a saving throw; you always take full damage.

Note that the saving throw occurs only *after* the spell is going to affect you; spell resistance/absorption/reflection is checked first. Here's what some of them do:
Regenerate Health: Slowly recover your health.
Rapid Healing: Cure Health effects (including potions) heal double. (I am pretty sure it's double because, with this advantage, healing spells heal only even amounts.)
Athleticism: You can jump about twice as far. (It may affect swimming, but I am not far enough to check, or movement, which I have not tested. (See edit))

I have not tested Regenerate Health + Rapid Healing; maybe I should. In fact, maybe I'll do that *right now*.

Edit: Regenerate Health doesn't appear to be affected by Rapid Healing, but that's the result of just one non-rigorous test. A rigorous test would actually involve an actual timer.

Edit 2: Athleticism does increase your movement speed.

I noticed one omission: You never talk about the Wounds stat, which can be changed at character creation (max starting wounds is 200).

Oops! Added to the original post.

Some observations about leveling up (since I have completed Level 1):

The increase in Wounds seems to be proportional to your previous Wounds stat. A YouTube video showed it increasing from 60 to 71, while my character's Wounds went up from 120 to 143. Hence, starting with high Wounds (especially combined with Rapid Healing) can be extremely beneficial in the long run.

A skill can't be lowered below its initial value unless you have something equipped that increases the skill, in which case it can be lowered into the negatives. Note that it takes 0 uses to raise a skill to 0, so it will rise instantly with the next level. Be aware that lowering a skill too far will actually cost points (below -12 or -14 or so).

The cost to increase a stat is affected by the amount you've increased the stat at the current level up. For instance, I can raise my character's SPD from 50 to 58, but no higher, yet I still have enough points left over to raise INT from 74 to 75.

From watching videos, it looks like you get more bonus points at higher levels. I suspect that the earliest you could max a stat out is somewhere around level 4.

Spells scale with level. You may have noticed that spell magnitudes are expressed as 2 ranges, for example, 2-20 + 1-6. The second range will increase with each level, so at level 2 it is 2-20 + 2-12. This means that many spells are more useful later on; offensive spells, for example, aren't that great on Level 1, but could prove to be quite useful on Level 7, especially if you can hit a lot of enemies with one spell.

A bit of micro-optimization:

Hand to Hand skill seems to give +1 damage every 7 points. Hence, you could do the following (assuming you don't use any piece of equipment that boosts this particular skill):

* Start with 56, 63, or (maybe) 70 Strength. In level 1, My Hand to Hand increased to 57, so that seems about right to not waste skill experience.

* Each level, add +7 to the skill. (Remember that you gain 6 levels during the course of the game.) Since the first level gives you enough points for about +8 to total stats, and the points awarded increase with each level, this is doable.

* Stop when you reach 98 (7 * 14). This is enough to get the maximum unarmed damage without equipment (and ignoring whether 99 or 100 STR gives you more damage). If you equip anything to boost your Hand to Hand, you will want to change the value so that you end up with 7x exactly.

Note that this is a micro-optimization (particularly the last point), so it is probably only worthwhile if you like doing the math.

I did a bit of testing, and found that Athleticism *does* increase your movement speed.

My general conclusion is that the advantages are really good and are worth taking, except maybe Acute Hearing and (for characters with decent healing capabilities) Regenerate Health. (When you can cast Cure Health and can regenerate SP's, you don't need to be able to regenerate health; just use your regenerating SP's to cast Cure Health.)

Also:

I still think Cure Poison is useless except for practice.
Shield seems to block a certain number of physical attacks (before checking to see if they hit in the first place) before wearing off. It does not appear to be that useful, but it seems to last forever if you don't get into combat, and hence is a good spell to cast before using an SP recovery crystal (but is it worth the points at character creation?) It is not worth using against Scamps, but might be useful against enemies whose physical attacks are actually threatening.