To answer # 4 - this is something which won`t be finalized until well into beta testing stage, however, as it is now, there are numerous defeat conditions and ways to end a battle.
-Player on the verge of defeat can surrender and offer terms (resources) - this can actually be done as soon as player is attacked, but the longer the battle goes on the more expensive it`ll be.
-If player fights it out to a bitter end, his Stronghold will take considerable damage and would need repairs. Some of your units will be lost, the rest will be resurrected with very low hit-points. So while it is a throw back, the penalty is not that bad - looking at around 10-15 minutes or so of repair/rebuilding time.
We try not to over-penalize loosing, but greatly reward winning.