As I remember, gained experience points distributed among characters. So, playing solo or with 5 companion have different effects on the game. BG is a roleplaying game and not all characters are needed in fight IMO.
I couldn't agree with you more. I've been doing great with my Trisha<Ranger/Knight; Shadowheart<cleric>, Gale<mage>, and Astarion<thief> Since I've learned the gameplay mechanics of the game the party has been able to pretty much handle any situation for which they have run into. Of course, we've not been to the Underdark yet.<LOL> But it seems that 4 is a good number any more than that would just be a pain in the ass.