Regarding the EasyTutu/Tutu v 4 decision, I'd like to state something that might seem obvious to some, but was really confusing to me.
EasyTutu is not an easier, quicker, less functional version of Tutu v4. It is by no means Tutu Lite. Well, it is easier and quicker, but it is offers all the features of regular Tutu using a simpler, less confusing installation program. Easy Tutu is only an option for the English editions of the game, though, so if you're using a different language game, this won't be an option.
So if you've got an English game, go with EasyTutu.
(edit: Apparently, the information about 'English only' is incorrect, but I have no way to verify that locally
)
If you're going to add any mods (and I highly recommend BG1 NPC over at G3), remember: If you want to modify Tutu, point the mod installation to the Tutu directory.