Yeah, that only sounds a little complicated

Ramseus' post about what you need for a good mod team above is spot on.  In addition, make up the general rules for your mod before hand, what is and is not acceptable behavior, who controls what, who makes the last decision, and how you will do your work.  Having these things decided, agreed upon, and documented saves headaches down the line.

Back on topic.  C++ is a good language to learn, but it probably won't help you as a modder.  When Dice/EA release a game they don't release the C++ source code, or even any API's for it, so you won't actually be programming anything.  That being said, with BF2, they did expose the game to some amount of programmatic control through the use of the python language.  It would make sense that they would continue this if they did release a BF3, since it allows the game to be much more flexible in the hands of a python coder.  So if you're interested in modding a potential BF3, learn python.  If you want to write your own game, learn C++.

There, you're now $.02 richer.