[Suhiir]

1 & 2) Just like SP-ATGs/SP-ATGMs helos are a "shoot-n-scoot" weapon system.
Myself I move at low altitude to a firing point and the following turn execute a pop-up and fire my missiles.
Of course the pop-up immediately attracts the fire of every AA weapon the opposition possesses. But you can get around this to an extent by having either scout helos or another attack helo (they usually come in pairs) skim along popping up and down (low to high altitude) at the extreme range of opposition AA capability to draw fire before your intended firing unit pokes it nose out.

3) For my part I've been rather disappointed at the "lookdown" capability of helos in general and TI/GSR equipped ones in specific. They very rarely spot opposition infantry until they move right next to it triggering an opportunity fire which very frequently damages the helo (even if its only small arms fire vs an armored helo).