Don't expect the 2 days/month and 2 weeks/year bit anymore. The Reserves are an operational reserve, not a strategic one, particularly if you go with an airframe like an airlifter (C-130, C-17). For this year, I'm looking at 2 days/month but also about 4-5 weeks between training and exercises. If we end up getting a tasking for deployment, I could go for anywhere from 2-6 months (2 is more likely though).
Anyway, you'll have to attend basic training and then the specific job training for your AFSC, whatever that ends up being. The length and difficulty of the 2nd one varies widely depending on what job you'll have. Some courses are only a few weeks long while some are six months or more.
I'm headed out tomorrow to my unit. I love getting into uniform and truly miss being on active duty. The Reserves is the closest I can get, and I have enjoyed it so far (only been with the Reserves for a few months now). If you have any specific questions, either post them here or send me a PM.
Major AndrewR, USAFR