I've gotten a few in the half-kilometer range. Since my cousin almost exclusively snipes (again, that's why my recon percentage is ridiculously high compared to other classes), he bagged a ~630m kill. I think it was off the carrier in Kharg Island.
The MAV is one of my favorite tools. There's a reason they called it Recon, not Sniper. They have a lot of useful tools up their sleeves that really aid a team, oftentimes outweighing the importance of sniping.
I believe the key to sniping is finding one gun that you really like (M98B, drool) in tandem with a particular scope, usually the 8x or 12x ballistic scope. This way, you get a feel for how much the bullet drops at certain distances. When counter-sniping, I usually hide behind a rock/tree/piece of cover, whip out my MAV and try to find my mark. If they're a newb sniper, they will generally make it easy for you to paint the wall behind them red.
I'm glad you're starting to enjoy flying vehicles more. I hardly remember how frustrating the jets were at first (except the new vertical take-off ones from B2K... that one blows). I feel right at home in one and there's ways to survive without flares, but it requires daring flying. I've had some pretty funny crashes, and I've had some weird, glitchy crashes where my jet bounces off the ground or clips something on the battlefield, but I take no damage and just slightly change course. All in the name of entertainment!
So yeah, I'll try to write up a concise vehicle guide, just with tips, no prose.