Is it part of the movement phase? or is it a charge as part of the melee phase?
If say a Goblin Tank does 3 impact hits on Orc Bikers, and all the Bikers fail their saves, they would die. But if some of the bikers survived, would they be able to attack back with close combat weapons?
And if its something like a Goblin Walker with CCW's, do you do the Impact and the Walker CCW's at the same time, or do you resolve the Impact hits separately before other attacks.
Ohh, and the last question, When a unit charges it always attacks first, does anything that dies get to attack back? or do only survivors get to attack back?
Also, if Impact is part of Melee, does it mean the vehicle moves away at the end other melee like normal?
Well, there is no melee phase. The vehicle either moves and shoots its ranged weapons, or, it charges and does melee (includi g Impact hits). In no case can a unit ever fire weapons and do melee in the same activation.