Yes you earn perks by killing. Shooting down planes air to air earns you fighter perks, bombing buildings and GVS on the ground earns you bomber perks, and shooting down gv's/planes/boats/buildings from a GV or a boat earns you Vehicle points.
Most planes/vehicles are free, meaning it costs nothing to take off in one.. and you really don't lose much by crashing one (except your pride... and any perk bonus you might get by landing successfully), however some DO cost points.
These planes/tanks/bombers cost perkies just to take out of the hanger... and those perkies you ONLY get back if you land successfully, so even though it may be faster, more powerful, more deadly... you still have to be VERY careful in how you use it because perk points are very difficult to build up when you're still a "rookie".
If you want to earn perk points faster, you might try flying planes with a HIGHER ENY value. Typically higher ENY planes aren't as good as their lower ENY counterparts, but you'll find that the kills you DO land pay muchos, muchos, muchos perkies!
Good luck!
