I'm almost new on VR photography. I try to improve my techique of shooting car interiors and I fell it is difficult. So I would very much apreciate a few advices and help from the community.

I have seen some very nice results on the web and I am wondering how they are done.
Some questions :
1/ how can I place my tripod. Is it outside of the car and the camera goes through an open window ?
2/ Should I use a fisheye like Samyang 12mm F2.8 on a nikon D750 or another lens ? 16mm ?
3/ due to the tigh place int he car, witch vr head is best ?
Many thanks for your help.
Marc.