I'm currently enrolled at UCB-X now so feel free to ask any specific questions. The structure - it's totally up to you. As the last person said, it's really designed for people that work, so most classes are held in the late afternoon, evenings, and there are some on Saturday, as well.
There have been students that finished up courses, took the MCAT and applied (and were accepted) to med school. I know that some people in my classes plan to do exactly that when it's time for us to do that.
There is a program advisor, and he would be a really great resource with whom to discuss the program. His name is Patrick Brown, and you can get his contact information from the Extension website. He can also explain the application process. Anyone can take classes through Extension, but you do have to apply to get into PBPM program. Some think it's worth it to apply; others don't.
Something that I also tell people - the UCB-X program is really designed for self-motivated people. They will send out information on opportunities and things to remember, but this program will NOT hold your hand. I know that is a turn off for some people, and it's something important to consider.
Feel free to ask any other more specific questions, and I'll do my best to answer what I can.
just thoughts...