I suggest nobody writes about the P-51 until the repair model is done. I'll give a couple of tips (including the po-2 as it's a capture the airfield favorite of mine).
Po-2
This plane is great for CTA, and pretty much that only. Unless you enjoy sightseeing in training mode, where the po-2 is also great fun. It's got a very low top speed, and no forward firing guns, so you can absolutely forget chasing anyone down. The great thing is you can come in to land from a steep angle, and still maintain a good landing speed. Other than that, you can use your rear gunner to defend yourself as best as possible (though it doesn't have much range) and use bombs to take out those planes already parked on the ground.
More plane guides later, I'm off to do a bit of playing right now.
I've got dibs on the A20G one, had much successes lately in that beauty.
Update:
A20G
This is one great bomber. It might not pack the biggest punch when it comes to bomb size, but it makes up for it in many other ways. It's fairly maneuverable for a bomber , so when flying you don't have to worry about stalling out. If you see someone on your tail, try to pick them off fast. You have a very powerful turret with a good range, and I've filled many a fighter with it. If you do manage to take some hits, it's ok. You can withstand a lot of body damage and still fly pretty well. When dropping your bombs you only have 4, and they aren't the most powerful so make them count. Slow down and line up perfectly. Than circle around for another pass, making sure to keep an eye on your 6 at all times for approaching enemies.