1. The biggest problem will be poor AC on the caster who is in melee range, which will result in the character being hit a lot; given the number of enemies that can appear in a single battle, this can be a significant issue. (Note that the remastered BT2 has more enemies per battle than either the DOS or Apple 2GS versions.) In BT3 you could eventually make a non-caster into a Geomancer, who can cast spells while having good AC, but that's not for a while.

2. In all honesty, I don't really pay attention to race except during character creation. In BT1, your stats will all reach 18 eventually. (Note that Gnomes actually have the worst stat sum, and will therefore take the longest to reach all 18s.) I don't remember whether there are any issues with classes being disallowed by that party (you *might* need a Bard at one point in BT3, and you definitely need one to complete BT2's (optional) starter dungeon.

My favorite parties are unfortunately disallowed by the remaster (that being parties containing only monsters and the empty party).

Thanks for the advice.

1) Hmmm, in that case I'm thinking maybe if I give that caster Dex 18 plus all the AC-improving magic items I find (shield staff, shield ring, bracers) maybe I have a chance... but it would still be a slog until I get those items. Perhaps I'll wait until I get those items first, then try swapping-out a Fighter-type and swapping-in a 4th caster later (who would hopefully level up pretty quickly).

2) The only class precluded by both Gnomes and Halflings is Paladin. (If I allow Dwarves, I could have a Paladin too).

Those magic items are needed by some of the usual front-line classes, like Hunters, to avoid getting hit even at 18 Dex. Mages don't have the same armor selection as those fighters, so will have a harder time getting a low enough AC to survive against hoards of enemies.

Leveling up a new spellcaster later is a viable option, especially given the way monster party members work in the remaster. A party of a single caster and a bunch of summons will yield as much XP for the caster as soloing with the caster, except that battles are much easier to win. So, a party of 6 demons and 1 mage can win some fights that would be much too hard to solo, and then yield tons of XP for the solo mage, leading to extremely fast leveling, allowing the mage to catch up very quickly.

In BT1 with legacy XP (which makes certain encounters repeatable), it is really easy to get a new caster up to archmage level (knowing every BT1-accessible spell) rather quickly; you just need someone who can cast something like Prime Summoning (which is only a 2nd level wizard spell in the remaster) to get started. (Note: In BT1 with legacy XP, Sorcerers and Wizards take much more XP than other classes to level past 13; this does not apply to BT2 or BT3, and it does not apply if you're not using legacy XP.)

With this in mind, it is not necessary for your initial casters to aim for all the spells; you can rush to get important spells (iike the aformentioned Prime Summoning) and then use said spells to level up casters who learn all the spells.

By the way, what Legacy Mode options (if any) are you planning on using? Some of them do have strategically significant implications.

Good point, I guess I'll have to see how it goes and whether or not I think I can squeeze in the 4th caster later or not. Thanks for the tips, could come in handy. I was thinking of sticking with the pure "remaster" rules (no Legacy options) to see how that goes, at least for now.

EDIT: Here is my final party roster:

Merry Nade - Hobbit Monk (M)
Lemma Nade - Hobbit Warrior (F)
Welyn Dowd - Gnome Warrior (M)
Sera Nade - Hobbit Bard (F)
Gwen Nade - Hobbit Magician (F)
Garr Den - Gnome Magician (M)
La Onn - Gnome Magician (F)

The four hobbits are all siblings :). I put the monk in the first position because he's got the highest Luck.

Update:

Once my casters reached level 5 they had enough HP to not die immediately in melee, so I swapped out my Gnome Warrior for a Gnome Conjurer (I also just noticed a mistake in my post above, one of the other Gnomes is actually a Conjurer already), so now I have two Conjurers and two Magicians.

I'm still in the sewers, but so far it's working out well.

As a side note, there is a different party idea I have had: 1 bard, 2 casters, and 4 monsters, which can work pretty well for the first 2 games. Here's how this could work:
* BT1: Have one mage learn Instant Wolf early , and then have someone aim to learn Prime Summoning as soon as possible. This will allow you to then summon demons to fill up your empty slots, and demons can be quite effective, especially since I believe they have a strong breath attack. Replace them with Demon Lords once you are able.
* BT2: You'll want to learn SPBI, at which point all you need to do is enter the Destiny Stone and get some Scathe Mages; if your party is full, they will *always* cast Mangar's Mallet during battle. (This is only true in the remake; for the original you'll need to dig deeper and get some Wacum the Wizards if you want constant MAMA usage.)

This doesn't work as well for BT3, however, as that game isn't filled with powerful monsters (at least as party members) the way the first two are, but at least you might find monsters that can cast spells like Restoration for you. With that said, some monsters have lots of HP, including some with over 10k, which is enough for damage to be irrelevant (but watch out for status ailments and critical hits).

Update 2:

I have finished BT1 and BT3 (I didn't play BT2 because it was my least favourite back in the day).

My final BT1 party was:
Hobbit Monk
Hobbit Warrior
Hobbit Bard
Hobbit Caster (all 4 classes maxed)
3x Gnome Caster (all 4 classes maxed)

I found the Monk to be overkill in BT1. Monk had lower AC than warrior, but warrior rarely gets hit anyway. Monk does more damage than warrior, but warrior can one-hit kill all enemies anyway.

My final BT3 party was:
Hobbit Bard
Hobbit Rogue
Hobbit Warrior/Geomancer
Hobbit Archmage
3x Hobbit Chronomancer

My deepest regret now is that I didn't use Legacy XP. Overall I found the games way too easy with this setup. After the first few dungeons in BT3, 99% of all battles were over in the first round before the enemy even got a chance to attack. I didn't run into any enemies which can resist my onslaught of spells until Malefia, and by that time I just used Safety Song because I already had enough levels and items.

I also think I should have used the Legacy songs/spells option, as that might have increased the difficulty a bit too in BT1.

Legacy save at guild only option would have been good I think, it would make the dungeon delves more difficult and strategic in BT1. More importantly it would reduce my temptation to save scum on level-up. I know I could have just not used quicksave, but easier said than done :).

Automapping and combined inventories were good changes to the game though, in my opinion they just removed some of the tedium.