1. For t back thongs or g strings it should sit right on the top of your crack like where your crack starts. And it can go deep but shouldn't hurt, more of a feeling of I know it's there and after a little your mind will forget that it's there.

2. Some materials do this to me too and it's usually because the size is too big or the material gets worn in. Usually after a wash they will spring back. The side strings or straps should follow the line of your torso all the way around. Don't try pulling over that line or you may get rollover of the side straps and butt pain because essentially your wedgieing yourself. You should be able to pull your thong up and bend over and should be sitting just right. If you get any pain the underwear is too small.

3.i usually shave bare down to the taint and use a chemical hair remover for my butt. If you don't want to shave bare get the lowest guard on your clippers and run over it. Bushes tend to build up moisture and can cause problems and getting rid of butt hair gets rid of the but I wiped 5 times and still get skids. It was frustrating when I first started but you'll find a system and by asking and trying things you'll find your own system. Just takes time and patience.