I think I might have a PPT on some investigations on disabled/destroyed Abrams from this previous war somewhere on my portable HD. If you want, I can ship it to you (pending, of course, a quick review to see if it's got any caveats or clearance requirements). I haven't heard anything about a 25mm round disabling an Abrams, but what can you do? Evil says he's heard of Iranian tanks destroying Abrams near the Iran-Iraq boarder... so, yeah.
As for helicopters, they're not supposed to be these heavy duty combat machines... (unless we're talking the Hind, who's sole apparent purpose is to attract all the ground fire it can)....