3. It's not supposed to do anything unless it's needed. Meaning it won't show a message BUT it will auto-accept quest sharing, trade-group requests and resurrect.
4. I haven't yet found anything simpler but switching on the other character. But I heard the group loot mode LootMaster (wrong?) is quite usefull when looting for a multi-boxer.

Can't help you about point 1 and 2, sorry.