This here is a good link for modding order and compatibility with Tutu:
http://gibberlings3.net/forums/index.php?showtopic=8122 Relevant for my questions:
I have installed BG1UB and BG2UB, and something is wrong...
BG1UB deals with BG content. BG2UBdeals with BG2 content. Tutu/EasyTutu ONLY has BG content. So, BG2UB will not do anything but mess up your Tutu installation, if you can trick it into installing in the first place.
I have installed all these great mods on my BGII game [or I have an error when installing a Tutu mod on BG2] , but nothing has changed...
What has probably happened is you are using EasyTutu, and you keep following directions that send you to add mods to c:\Black Isle\BGII - SoA. When you installed EasyTutu, it left a clean Baldurs Gate, and a clean BGII - SoA for your gaming enjoyment. Now, all the Easytutu/Tutu mods need to be applied to your new, shiny BaldursGateTutu directory.
If you are using the older Tutu v4, you only have two directories - one for BG and the other for BG2. Adding mods to Baldurs Gate will not have any effect on your Tutu game. You will need to add them to your BG2 game, as it has been converted to use BG content, but is actually a modification added to the BGII - SoA game.
I installed BG2 Tweakpack, and nothing is chaned in my EasyTutu game...
BG2 Fixpack will have no effect on EasyTutu/Tutu v4; EasyTutu has the relevant fixes applied already, and with Tutu v4 you will have better luck moving up to EasyTutu. BG2 Tweaks, though, is designed to be used on the BG2 engine, so it will work beautifully on EasyTutu, Tutu v4, or BG2... provided you have installed it in the right place. Please chack to make sure that you have applied it to your EasyTutu game directory, not your BG2 game directory, if you are using EasyTutu. (If you are using Tutu v4, the BG2 directory is the right place).
Apparently BG2Tweaks was okay to install in the Tutu folder, since it runs with the BG2 Engine.