Ok so my question is.

Lets say you have one hull left, just enough to Vader, but you and your opponent both have the same PS and he has initiative.

So he gets to shoot at you first, but because of simultaneous firing you get to return fire.

If you were to be destroyed and get your return fire, can you still Vader?

This is basically more of a question when is damage applied in terms of simultaneous fire.

Is damage applied after both ships fire their volley?

Is damage applied immediately, thus its not really simultaneous fire?

All I could find is that the ship gets to keep and use all its upgrades during the return fire, but if the damage is already applied to the **** and it should be destroyed, you technically can't Vader because you don't have the hull for it. So then its not really simultaneous fire.

Check the FAQ, you'll find your answers. https://images-cdn.fantasyflightgames.com/filer_public/c8/0c/c80c62ee-3c2f-4370-83a8-a5851b68c44b/x-wing_faq_v422.pdf

Simultaneous fire is not really simultaneous, that's just the name the rules uses for it. The damage is applied well before the second ship gets to fire, and thus, you can't use Vader crew when you're shooting after being destroyed by Sim. Fire.

Similarly, if someone with the initiative and the same PS tractor beams you onto a rock, you can't shoot.