Agreed that as they are *not* disembarking, they appear where the vehicle was destroyed.
1. The transported troops can attack after the vehicle is destroyed by OW fire, or in the assault phase after the vehicle was destroyed by CC or FF. Usually they may *not* fight in the assault phase that the vehicle was destroyed unless it was destroyed by First strike (see below).
(Note, some vehicles allow the troops inside to take part in the assault using their FF) 2. Yes.
Quote:
Weapons with the first strike ability attack first in an assault. Resolve the attack and inflict damage for the weapon before any enemy units make their attacks. This may result in some enemy units being destroyed before they can attack.
So, in the case of transported troops it may result in those troops being available in the 2nd "normal" round of combat.
3. The troops that fall out of the vehicles fight in CC if they are in B-B, else they will use FF.
4. The rules regarding destroyed vehicles applies irrespective of how and when that happens. So the troops still need to test after the vehicle is destroyed by a Dangerous Terrain test, or a hit from Assault or enemy shooting (and may still use an "invulnerable save" against MW or TK hits)