Very simple question, I was wondering what anyone could tell me about what the individual models are made of?

Plastic

I would guess modeled ABS plastic

Well most of them are still flesh and blood but a surprising amount contain considerable quantities of silicone.

Oh, wait... you mean THOSE models....

Based solely on the look and feel, I'd say injection-molded ABS. This, by the way, means you can glue styrene bits from model kits to them if you scrape away the paint, because some glues like Ambroid Pro-Weld will melt and fuse ABS to styrene and vice versa.

So, on a somewhat related topic, I was wondering if, when you get an X-Wing with slightly misaligned guns, can we dip these in hot water to straighten them out, or will that ruin the models? I'd hate to go from a bad situation to a worse one.

Thank you for the comments! Just wondering because I'm considering painting.

Also, my YT-1300's base is a little warped on one end and it wobbles.. Any thoughts on how I can correct it?

Thank you for the comments! Just wondering because I'm considering painting.

You can repaint, but the paint tends to rub away as you work. I tend to get a base coat on them then give them a blast of Gloss Varnish. This seems to seal them enough that you can work on them fine.