There is discussion on I think the macro forums about a way to make your other screen accept quests and turn in quests without switching, but personally I just keep the main screen windowed in a very big window (90% of the screen at least) and the other window clickable in the space that's left. I click over to the other window and loot and turn things in like that. It's not much more time consuming at all. You can also have an auto-accept macro for trades and quests so that you can share quests with him and have him accept without switching.