I couldn't see getting a single action. Guess they have their place. You would have a little more control than rattle cans. But about 1 1/2" to 2" spray would be the best I would think you could get. Then you have to clean them. For that much control I would stick to rattle cans.
Do yourself a favor and get a decent gun to start out with. Doesn't have to be top of the line. Paasche or Badger are about starter brushes. Both are about $60. You are going to spend $20 on a body, $3 for each bottle of paint, $5 or $10 for a mask. And so on. Why buy the cheapest airbrush you can find and screw all that up?
Same thing with a compressor. Get the best ya can. I got a 30 gallon Craftsman. Wish I could have got a 60 gallon. They all make a lot of noise. The smaller ya get, the more they run. You will be using it for something else. I would put money on it.