Model airplane questions?

I have decided that model airplanes are really cool. Especcially the battles… So I was wondering. What size plane do I use? A big one? A small one? Also were is there a place were I can compete with others in Tucson, Az? What will I have to sign up for? And last question. What are the rules of battle? Remember model rc airplanes. Thanks!!!
Usually air combats we use small park flyers. Reason being
1) Rc planes are not toys, they can cause substaintial injury or damage if mishandled. The larger it is, the more injury it can cause.
2) air combats has high chance of damaging the plane. Larger one cost more. Small cost aint cheap either.

Try looking for a local club to learn how to fly one first. Read up at the rc forums.