"can someone explain to me a little about combat aircraft and what they do?"

Hi performance 1/12th scale or special purpose used to 1) tow a 30' streamer and 2) cut everyone else's streamer off.

"are they glow engines?"

Yes. While electrics are allowed by every set of combat rules I've read, they do not offer a competitive power to weight ratio.

"do you actually shoot each other out of the air?"

No. The object is to tow a streamer and save your own while cutting off everyone else's.

"any basic info or a link to a cool noobie web site would be cool cause if so it sounds like something i could get into."

Absolutely:
www.rccombat.com/rcca.asp
One of the best sites on the web with truckloads of information!

Warning: R/C Combat is VERY addictive!

HTH,
D