How do they work, I mean what are the rules on them. Does every member have to be from the same team? or does each member get their team ability no matter what?

I'm completely confused on this matter.

Each member gets their own ability no matter what the rest of the force looks like.
Some TAs may only work if you have two or more figures that can use that TA though.

Thank you very much. That makes alot easier to decide how to build my team.

I can feel you on the confused thing. When I first got into the game many years ago, the complete lack of a local scene to ask for guidance had me and my friends confused on the TA-thing. So for a long time we erroneously thought that there had to be more than one member on the team for the TA to work.