What does having multiple attacker pilots do for you?

Mess Room
1

I’m not sure what having them available and using exp in the tech tree does for me? Can anyone clear that up?

2

Currently nothing, in the future they can main rear guns and such i believe.

3

Nothing, they dont even belong to you.
I once curiously paid 2 bucks to unlock more crews, and landed on the ground, that pilot dosent even in my squad! It has blue icon ,not green icon, and can not switch to him!