Hiya,
Glad you liked what you saw.

Boy, you have a lot of questions. Let's see, you can get detailed answers for all of them on the RCCA website, www.rccombat.com
but here are some short answers

What are planes built from? Yes, to all of it. There are kits, there are guys who design and build thier own designs. The RCCA site has lots of links to guys who sell kits, and also information on where to get component parts. www.georgiacombat.com also has a pretty good list of a variety of combat kits out there, though it's by no means "complete". www.SpadToTheBone.com also has a lot of combat designs. Even if you don't want a SPAD wing, you can mate a SPAD-type fuse with a foam wing, or a foam wing to a SPAD fuse. Whatever suites you.

On wings, there are guys out there who will custom CNC cut wings to your specifications, or have some general "normal" wings available for you to put on whatever fuse you come up with. Many guys cut their own as well. I cut some of my own, and order some of mine from Hattrick (link on the RCCA site). The normal way to cut foam is with a hotwire. It can be on a bow that is manually held an controlled, on a drop arm table that moves the bow for you using gravity, or hooked up to a computer and stepper motors for a CNC system. Personally, I'm using a drop arm system, but I don't have it quite perfected yet.

The RCCA site also has a calendar of events, so you can check there for other contests in your area. Or check the RCCA forum under "upcoming events", or send some email to some of the RCCA folks in that area (again, you can track down individuals on the RCCA site) and I'm sure they will give you the story on the next contest in that area.