whats the fewest number of characters i can have in my party and still be safe? i need yan for detecting traps, aerie fro clerical-mage spells, my guy could be a fighter, do i really need anyone else?

Sounds like you want to solo but are having second thoughts ;). Perhaps you should get your feet wet with a four-person party. You as a fighter type (fighter, paladin, ranger, and/or kits), Jan as your mage/thief, Aerie as your mage/cleric, and last you will probably want another fighter type like Valygar, Mazzy, Minsc, or Keldorn.

Safety is relative in this game. I have beaten guys in solo games with littel problem that have wiped out one of my six-person parties in no time.... It is a function of tactics, die-rolls (chance) and the situation. So, technically, there is no reason that you cannot take any 1-6 characers of any class and make it through the game... Yet, the fun and challenge of the game, at least for me, is exploring the strengths and weaknesses of each class and party combination and developing tactics to maximize those strengths while minimizing the weakenesses...

Take a look at some of the solos or stories other people have done and you should be able to see possibilities for playing that you might not otherwise have considered.

I've had lots of parties of 4, but I think I'd not go below 3, except for that one time I played with a 25/25/25/25/25/25 fighter/thief. That was a one time thing I did when I just found the cheats in BGI and imported my character in BGII