With EasyTutu and BG2, you will have two separate folders, one for your Tutu game and your Tutu mods, another for your BG2 game and your BG2 mods. EasyTutu indeed leaves your BG2 installation intact. (Before you start installing mods, I recommend reading this topic:
http://forums.pocketplane.net/index.php/topic,17555 - it will make your reinstalls much easier. But since you've already installed some mods for EasyTutu, that's a moot point for now).
Flirt Pack and Romantic Encounters definitely work together. If you would like more romantic possibilities, Romantic Encounters would work for you. They are both BG2 mods - do NOT install them into EasyTutu folder. EasyTutu folder is for BG1(Tutu) mods only(read the readme of each mod to check if you like).
Best of luck. If you'd like more help, feel free to ask here, in Mod Discussions forum(or in specific mod forums, if your questions are about Flirt Pack/Kelsey/Xan/Banter Pack/other mod).