Lieutenant and Isolated

These answer are for N3:
1) Yes, provided this hasn't triggered Chain of Command.
2) Uncertain.
3) Yes.

Isolated prevents you from using orders from your order pool, the LT order is not part of your order pool.

 

I'm assuming your Lt got isolated during your active turn, before you spent the Lt order.

1) "Isolated" says the troop can't receive orders from the order pool. "Special Lieutenant Order" says "this order is not included in the order pool." So I would say yes, the isolated Lt can still use his Lt order.

2) "NCO" says the unit considers the Lt order to be "another regular order of their combat group." It doesn't explicitly say whether that means it considers the Lt order to be in the order pool. I would say probably being "a regular order of the combat group" implies being in the combat group's order pool, meaning the isolated NCO troop could not use that order.

3) I would say yes. The Lt becoming isolated doesn't have any effect on the Lt order itself as far as I can see.

It only matters during the turn in which the Lt became isolated. During your next tactical phase, you will go into LoL and not generate an Lt order.