There are some things that are basically hard to distinguish as "better than the alternative", so I thought maybe some inquisitive minds could do that here. Obviously, I have a few questions to begin with.

1) What is the best point to start building economy buildings (mills, mines, etc.)?
2) +2 HP or +1 Defense on swordsmen at levelup screen. Which one would you pick and why?
3) Any nice ways to get Defender's medals efficiently (even knowing the requirements, I find them way too rare, especially due to Will for Victory ones)?

Please contribute =)

1) As soon as you have the extra resources and don't need to build anything else. Get New Horizon mod, it helps with that a lot, giving you plenty of other buildings.

2) Defense. I think, not sure, but I think, it's less straight math, than it is formula type thing. I.E. It's more like Age of Wonder where defense blocks a portion of the attack based off defense value, and not straight add/subtract like Heroes of Might and Magic.

3) No idea. I use a commander for the most part, and tend to earn a medal a battle for at least one unit. I focus him on first Initiative raising, then defensive raises, then offensive(I tend to leave off Logistics. If I do it right I never cost too much for even a maxed out army, and the bonus to Siege isn't enough to bother with.

Well to answer your 2nd point I have to say for Swordsman units I would take the +2 HP over 1 Defense. UNLESS your HP was so high due to those crappy medals and your defense was way low.

I choose my level powerups in the following order/proirity 90% of the time.

Parry
Resistance
Defense
Counter Atk
Forced March
Stamina
Attack
HP
Ranged Def
Morale

Now if any of these, other than Ranged Def or Morale, has an option for +2 that would most likely go to the top of the list. There are exceptions ofc esp if you had a Swordie with 3 of those Victory medals that give +2 Atk/CAtk well then you would really want his HP before any more atk bonus's really so that he can survive.

The only medals I allow my Swordies to have are the Defenders, Victors and Hero Medals. I actually ounce had a level 4 Swordsman with 2 Hero Medals, Parry x2 and Forced March already. He got a 3rd Hero medal within 2 more levels I believe as well. Was so great having him protect my Wizard :)

1. I'd say once you have all the urgent stuff you need to keep raiding sites for a while. On small shards never.
2. Defense , it will block one damage each attack.
3. Yes, you have to let the unit end the battle with wounds. You have to try to take about its full hp of damage, kill an enemy and let it survive with as little HP as possible. But dont let it take too much damage or use too much stamina or you will get offered the hp or stamina medal. The exact formula is somewhere in an older thread about medals.

1) Basically, never. You always would need to build storage houses(repair/stockpile loot), libraries(swap spells, mostly for mages), forts(meatshield, defence), the more heroes you have - the more supporting buildings you would need. Then you would need roads of stables...
2) Health. Universal damage soak.

For swordsmen my priorities:
1. Forced March
a)Lets you take vital positions faster,
b) lets you make "Forced march - step back-get heal-return to position"
c) lets you jiggle like:
A(S1)__B(S2)
C(S3)
S2 - heavily wounded, S3 uses forced march, steps away, S1 uses forced march, steps on C, S2->A, S1->B, S3->C
So, you close wounded S2 from attacks without making a dent in your iron wall.
d)lets you waste stamina to decrease attack/counterattack, enables resting for prolonging fights or having weak units between swordsmen and tough units. (like you can rest while basilisks scratch you, and safely shoot hydra with scout).
2. Health - universal damage soak, poison, magic attack ignore parry and defence.
3. Defence - bread
4. Counterattack - butter
5. Stamina
6. Attack

Leftovers:
Parry - works ONLY on first opponent's attack. Doesn't work on your own attack, when used rest, on all subsequent attacks. Personally, I don't pick it. Though, there is a trick - when defence+parry>opponent's attack+10, they wouldn't attack swordsman, because they don't have any chance to deal damage. So, some players max defence+parry. I don't like it - I want from enemies to attack swordsmen and get damage from counterattack.

Resistance - swordsman can have maximum 4 resistance. In early versions Hero's cross was easier to get(didn't have "lose 66% hp", only "kill 5"), so it was very high priority stat to obtain 6 resistance - immunity against Disease and vulnerability. Currently it is useless stat on them, take hp instead.

Ranged Def - They have enough innate to not care about T1 and most T2 units, and enough HP to soak damage from catapults.
Morale - swordsmen don't have 20+ damage to bother with morale.

Medals: best case - 2 Medals for Resilience, 1 Order of the Defender, don't mind having 3 of the same.

3) Use forced march while enemy approach, then use rest while they attack.

There's not an easy answer to this, since it depends on circumstances. Clearly, as some others have posted here, it is unlikely to make financial sense on smaller shards.

On the other hand, a mill can be upgraded to a brewery which improves population mood. If you're on a shard where mood is a problem (e.g. an undead world shard in MotBW with a global -1 mood modifier) then building those becomes more significant. The granary/stable upgrade is another example, and likely the most popular one.

Holy Jesus. I lack words to describe how grateful I am for this tip. Up till now I honestly considered Forced March to be on par with Morale (aka useless). Now, when you me me realise that it's a great stamina waster, I'm getting a LOT more Defenders medals.

Thanks a LOT for this one.

How can you consider mobility in battle useless at all?
Forced march, 2 steps, astral energy, forced march, 2 steps - and your swordsman reached pesky shaman in one turn.

Wow! Tips using Forced march to soak stamina are very, very helpful. Many thanks for that.

Perhaps I dumb, but I don't really understand the reason behind "Use forced march while enemy approach, then use rest while they attack." Is that for keeping weak units alive? or to have better position on the battlefield? Or something else?

Formulas for medals:
http://www.gog.com/forum/eador_series/award_medal_details_request_to_russian_speaking_friends/post2
For medal of the defender you need to take a lot of melee damage, but if you deal damage with counterattack, you can get damage medals instead.

Additional use:
See attachment.

Mechanic: lizardmen and basilisks reach swordsmen first, scratch for 1-2 damage, you DON'T touch them with rest, so medusas and hydra can't reach them. Archer safely kills hydra and medusas.

Thanks for the clarification, Gremlion! That's a very smart tacit. Awesome!

That's a pretty nifty tactic. I'd never considered purposefully leaving weaker enemy units alive to act as a buffer zone against stronger melee units. I'll have to give that one a shot myself.

Another of those silly questions: what's the exact % of exploration when harder dungeons start? Is there a difference in rewards between defeating such dungeons at >90% of exploration and same dungeons in the next ring?

I don't think exploration % is linked to dungeon difficulty (or rewards) in any way. My understanding is that all of the locations are determined when the map is first constructed, with difficulty weighted by ring (although you can still get the occasional strongly defended site showing up even in demesne or ring 1). Exploration only uncovers existing locations, locations aren't randomly generated during the process of exploration (now, there are some random events and encounters that can occur during exploration, but locations aren't one of them).

I'll now await any errors here to be corrected by Gremlion.

Map generator have a rule which forces it to place rare resources deeper in the line. Some sites prefer to be hidden after generation, but there is no rules for exact%.
"Random events" during exploration, in fact, are sites too. If your hero has found undead - ambush - dragonroot - orcs, after reloading and exploring province 100 turns later with different hero, you would find the same undead - ambush-dragonroot-orcs.

Reward is based on quality (level) and quantity of the monsters. It is possible to find guards with similar quantity, but different levels of the monsters, and, obviously, harder encounter would give more reward. Due to random factor you can get harder encounter closer to demesne.