i just beat the catacombs under candlekeep and before i was going to go to
baldurs gate i was wonderin what kind of arrows i need to get and bullets and what potions i could take so i dont have keep running back and forth.
about the party should i have 5 shooters and just one tank or should everyone
in my party use a missle weapon.

Well if has been quite some time for me since I played but I'll give you what I can remember.

Missles - +2 bullets for your sling throwers; as for arrows my all time favorite is the Ice ones because there is no saving throw against; also get +2, Fire but I would avoid detonation because there is a tendency to do real harm to your own party.

Potions - Heal (of course), Giant strength, Protection from magic (I'd have scrolls of this also)

* Just equip yourself the very best that you can and be wise with your
memorized spells. I would have at least two Tanks, but even my
Tanks would have missle weapons.

*** One other thing. If you have not played Tales of the Sword Coast do
yourself a BIG FAVOR and install it NOW, play out the offered adventures and
THEN finish out the game. You can pick up TotSC cheap!