1) Any one territory of your choice (that doesn’t already have one, of course). It works like any other IC.
2) Your sub must either fight or move away in combat movement.
3) His ships must either fight or move away in combat movement.
4) No, nor after being offloaded.
5). Fighters launch before their carrier moves, so they both begin their movement in the same sea zone. Likewise, fighters land after their carrier moves, so they must both end their movement in the same sea zone.