1. When i import a character it has none of its stuff in inventory. is it meant to be so?
In manual or when exporting/importing is text "character will lose any bags of holding, gem bags and scroll cases when imported." why bother to say this if you lose everything?

2. what is this stronghold thingie everybody keeps talking about. heard somewhere that warriors get stronghold, mage gets mage guild, cleric a temple etc. where?

3. what quests are lost when playing in multiplayer?

When you start the game you lose everything anyway so the only way around it is to start a multiplayer game THEN import your character(s)

Every class (nearly) has a diffrent stronghold, each one is obtained through a quest, and every quest is diffrent, if you want spoilers ask and you shall reccive all the data.

The only quests that are lost are the ones you only get when you have a specific NPC in your party. The rest are all inculded