Only the Barbarian will be able to use two weapons at once. For Diablo II, we have increased the amount of weapons that are reflected upon your character.
Socketable items are user modifiable.
Placing a gem gives the item a beneficial magic effect. The rarity of the gem determines the strength of the effect. Blacksmith NPCs can repair items. Be warned, the cost of repairing worn down magic items is quite high. Yes, we have four different types of crossbows.