So a friend and I have heard good things about this classic RPG and decided to give it a try. We've got BGT installed on both of our PCs and its running well. I'm not sure if we are going to run into an issue with the xp cap though. I'm playing a swashbuckler and will be dualing to a mage at 10. Friend is a gnome cleric/illusionist. We plan on each controlling one NPC for now as well...so a party of 4. I know the xp caps are different among games but didnt know how BGT effects that. Any ideas?

By default, I think BG T limits you to the xp cap from the expansion of the second game, Throne of Bhaal, which is 8 million xp, about level 30 for most characters.
After all, BGT makes the whole series one big game, and there's no way for them to set different xp caps for different parts of the game.

OTOH, there just isn't that much xp available in BG 1 + TotSC, so you probably won't end up too high to lose all challenge in the game. If you really want to set appropriate xp caps, maybe you could use this mod, it gives you several convenience options, including changing the xp cap.
Of course, you'd have to uninstall and reinstall it for the BG 2 part of the saga.