RE: foam or balsa?
For indoor aerobatics, foam is the only way to go. Ive yet to see a good balsa indoor 3D plane. Balsa planes just end up too heavy for decent indoor flight. If your just getting started in 3D flight, foam is the way to go. You'll probably smack up quite a few learning how to hover, harrier, etc. Its far better to smack a foamy than a balsa plane. Most foam planes can be easily repaired in minutes with a little CA. Balsa planes will take considerably longer, and cost more to repair.
Just remember with balsa planes, you're pretty much limited to outdoor flight, and repairs will be more time consuming and costly. Balsa planes can also be fun though, so you shouldnt rule them out all together. There are quite a few electric balsa kits that would provide lots of fun. Fliton has some top notch balsa electric kits.
Foam
Pro's - Easy to build, Easy to repair. Lightweight for indoor flying, Lower cost due to cheaper materials.
Con's - Less ridgity, means they tend to flex during flight, which requires carbon reinforcement. Easily pushed by winds during outdoor flight.
Balsa
Pro's - Fly more like glow planes, are available in full fuselage kits (vs profile. Cut through the wind better.
Con's - Can be more costly due to more powerful equipment needed to fly them. Require more time, and extra cost to repair them if broken. Unable to fly indoors due to speed or weight.