Availability of full-time positions varies by unit. Some units have full-time positions open up on a regular basis, others have a long list of guard bums waiting to get a full-time slot. There are two kinds of full-time positions.
AGR (I forget what it stands for)- traditional full-time military job like you're used to. Same pay and benefits as active duty. AGR's also may qualify for the bonus. Similar to TAR, except you stay in one unit instead of moving around.
Technician - State employee whose full-time job is to work at the unit, and whose part-time job is as a traditional guardsman. The big advantage here is pay, you get paid for both jobs so you can make more money (probably not more money than the guys on the bonus, though). I think that benefits vary by state for these positions.
I'm sure other folks on the board can fill in some of the details on both types of jobs.
Good luck.
T1bubba