Wow - to properly address that question would take pages. As you seem to already know, there are many many different team models as there are teams. In this forum you will really only get the FRC and some FTC perspective.
We use a combination of technical mentors (no teachers, as we aren't in a school), non-technical mentors, parents, and student leaders in a variety of roles. You can get an idea of our team structure in our handbook at
http://moe365.org/teamdocs/moe_handbook_2008-9.pdf