Plane,
I was in a Stinger unit when I was in the Army. You can use Stingers to hit ground armor (and I hear it does work wonders). I agree that the Stingers in the game are pretty unrealistic because the real life Stingers are Heat Seeking. When you fire, you have to Super-Elevate them so the rocket doesn't hit a target on the ground. The iron-sites on them aren't accurate in the game, and in real life, they are more accurate on hitting heat emitting aircraft. They are short-range weapons and aren't effective against fast-movers like Fighter Jets, but very very effective against Helos and UAV's.
For backblast, you can try adding something that would cause injury, flame, explosion that occurs when behind the weapon when fired. I've seen a few addons that have a realistic backblast, but I cant help you on which ones they were.
Some weapons in OFP aren't realistic. The AT-4 that the BAS Special Forces use are single shot weapons, and cant be reloaded. They dont have a backblast, and they are more powerful IRL.