Hi Zophyael
Welcome!
Wally will give you a more detailed run through
My small addins
You don't need to be in a team to take part in the racing.
Having all DLC would be a good idea as most of the servers run content (cars/tracks) from all of them.
There are a few pub servers to jump on and race on to get used to that a few of us drive on.
(Search for "XGN Marty FTW") good mix of cars in all.
Some of those servers run MR (
http://www.minorating.com/Project) so you will have to improve your rating from N to either ABC to join in on most.
If you are going to be a permanent edition to XGN Marty whitelists your GUID to jump onto his server
(I've been to lazy to do for mine, but I also don't have everyone's GUID as an excuse too)