I did use it on my bikini area after shaving and it feels and works wonderful! I use to use A&D ointment after shaving, cuz my skin use to get irritated when my underwear would rub...but this stuff worked great and no irritation.
I was wondering the same thing for the thighs....in the summer when it too hot, sometimes I need or use baby powder, but I'm gonna try this. This sounds gross too, but I also sweat under the breast area, and in the summer can become "cough" a bit raw. So I'm definitely gonna try this if/when that circumstance arrises.
As for a foundation primer, I put foundation on over it today and first I love how it evens the skin out and smooths it. Then after applying foundation, it looked and went on sooooo nice. I still got a bit oily, but not like I use too (so yes I still needed to blot, but only like 2 times so far, normally I could blot ummmmmmm 10 times or close to it).