Number 1: All of the NPC's have their own story. Some are funny and others are enchanting. They will only tell you so much of their story at a time, as you have found out. Their tales are completed about the time you are in the last chapter. You should try to pick an NPC based on what you need. If you have a Wizard you should probably get a Fighter or Barbarian. If you are a Fighter a Cleric, Rogue or Bard would be nice. Personally I really enjoyed Linu's tale.
Number 2: In chapter One you should go to the "Shining Knight Arms and Armor" store. If you speak to the Half-Orc in the front and follow the "Premium equipment" line of inquiry you will recieve the wardstone that allows you to go to the back of the shop and go downstairs to meet Marrok the dwarven smith. He can forge items for you. Farther on you will find another forge in chapter 3 I believe.
Number 3: None. It's just dressing for your character.
Note:
You should check out some of the user created mods. They are a blast.
Neverwinter Vault has tons of them. They can add alot of flavor to the game.
Personally the Penultima series is a hoot. There are a number of the PnP D&D modules that have been converted to the NWN game as well. Take a look it is well worth the time.
http://nwvault.ign.com/Files/modules/