At Endor the ISDs arent that hard to destroy
1) youll need almost every power up from the other missions (advance shield, advanced protons, laser tech, homing protons, etc...)
2) take x wing or b wing if you need more shield power
3)on the first part dont worry about wasting ur homing proton torps on the bombers.
4)on the second part this is what i do(if u aint looking for gold):
i call my wingmates to form up and head up to the ISD on the left, and even if i attack all the way from the front the lasers dont concentrate all their fire on me (i try to keep a bit high, anyway), on the other hand they fire my wingmates and several other rebels that fly around there. I take the two power generators on top with the help of my wingmates and then head down for the one underneath. afterwards do the same with the second one.