You CAN evade a Hellfire incoming, but it's one of the hardest things you can attempt. The best way is to be close enough to launch a Vikhr that will hit him before the Hellfire hits you...if you make him break off to try and evade your missile, his loses lock!
The other thing is terrain masking. The thing can't go over the hill and drop down on you.
Does anyone know if the Apache have a laser warning system modeled? If you have your laser off until you're in range, and you're coming up from the side, can you delay his warning of your approach? As I said, I usually avoid them, so I've never tried flipping the laser off to try and be stealthy.
As for rockets, I usually use them when I'm out of bullets!! Unless it's a big cluster of units, where the rocket dispersal helps out, I prefer the gun...it works at farther distances anyway! I think my record is 4 kills with rockets with the standard pods, and that was infantry in a group IIRC. For like 20 rounds of ammo I can get the same result.
The Jedi Master