Is it ok to use omods and bain installation together?

Yes, you can. But then you lose most of the magic of BAIN if there are mods not added by BAIN, and it can't let you know conflicts and tell you where those files came form.

The only mod I use OBMM for is sensual walk patches by Surazal, and Dark Darn UI. The rest is from BAIN.

Yes i have darn ui as bain. Just find it hard to confirm files to bain like QTP3. Got to get use to it.

Well, you don't have to make a complex BAIN package with QTP3. You could make a simple package with 7z, such that all the "texture" folders are within "data". That way, you install the whole thing in one go. You cannot selectively choose which particular textures you want - it is all or nothing.

This is exactly what OBMM would do for you too. SO you can use BAIN for that as well.