Raison D'Etre

I've run into some questions about monster pack install, provided by erebusant.

1. How does it handle character progress after finishing BG1 part and going to BG2, do all NPC's remain with stats, developed previously? For example, if i dual Imoen to mage at 10th thief level - will it remain intact or be changed to BG2 version? And also can anybody provide me with good advice at wich level should i dual her to mage?

2. If i want to install some additional tweaks, for example one of the G3s - should i uninstall all mods below BP and then install tweaks, then refinements and map back? And will i be able to use old saves with installation of G3 tweaks?

Thats all for now, thanks.