the a-10 and 25, can shake off quite a bit, but they can get killed with 1 as well, now the huey and the hip, i always found them to be ridicolous, the pilots seem to be more like terminators than humans, and both seem to have some alien sheet metal, that has the strength of tank armor.
Now as for everything dealing damage to everything its kind of annoying, that the game doesnt have different damage properies for different vehicles coded in, but im sure well get it at some point.
On the plus side the improved AA is great fun, and gives pilots a run for their money, its even funnier since you can instantly see who's a good pilot and who's been playing too many shooting range missions.