That level of bike is fine for someone just getting into the sport; if you get really serious about the sport you'll probably want to move up the ladder in various ways. It'll take a while to absorb all of it, terminology as well as just learning how and where you can ride your bike. Just remember to keep grinning and welcome to the madness.
Rigid bikes are those with no suspension. Hardtail means the bike has suspension in the front only. Full suspension is front and rear.
Lots of things about bikes at sheldonbrown.com, some technical, some not.