Ahoy, spoilers ahead!
A) I myself is very fond of the long sword +2 which you obtain from Greywulf at Nashkel Mines, but statistically best is Drizzt's scimitars (both +3, though one gives +2 AC and the other 50% fire prot, IIRC). Also there is a two handed sword +3 to be found in Durlag's Tower and Spider's Bane in Cloakwood. Essentially best is Drizzt's blades, however, atleast IMHO.
B) This is a very subjective matter, but I'll give you my opinion(s):
- Armor: The Shadow Armor (bought) in Beregost is nice for a thief and Drizzt's chainmail can be worn by spellcasters and thiefs alike. On the heavy armor list, I personally have Ankheg Plate Mail on the top, along with the plate mail +3 found in Durlag's Tower.
Robe of the Archmagi (good/evil/neutral according to AL) is the best robe to wear.
- Cloak: Not my coup of tea. Somebody else will have to complement here. (Edit: though Cloak of Misplacement is good.)
- Helm: Helm of Balduran found in Baldur's Gate, though Kiel's Helmet in Durlag's Tower is good too.
- Shield: Large Shield +2 in Durlag's place, and Kiel's buckler (same location) if the first one is to big for ye.
- Boots: Boots of Speeeeed. They'll never see you coming.
- Amulets: Same as cloaks.
- Rings: Definitely the insane Ring of Wizardy. Best item in the whole game, IMO. Also Ring of Protection (+1 and +2) for non-mages and Ring of Holiness for your priests.
Not on the list, but very good anyhow: Gauntlets of Weapon Expertise. +1 to THAC0 and +2 to damage is not so bad.
Also, if you think I'm just babbling, there is always the equipment sections on the [url="http://www.gamebanshee.com/baldursgate/"]Baldur's Gate site[/url] here on the page.
Edit: Woha! When I started to write this post, there were no answers in the thread. Took some time to type and recall I guess. 