A) Nothing, just totally naked
B) What you’re wearing and anything you carry with you (even if you’re not carrying it right now) like a bag
C) What you’re wearing, what you carry with you, and the contents of your home (it will be teleported within a few hundred metres on the surface in an accessible location, but obviously won’t be connected to any services like electricity or water)
The diarrhea is going to be one of the biggest challenges. The differences is food, parasite/microbiota challenges… dehydration and acclimating to the local food supply are going to present problems.
You’ll probably be killed for washing your hands before eating or something.
Eh. Some traditional cultures do that anyway. I highly doubt they’d freak out over it, let alone to the point of violence.
They might think you’re weird, and you’re probably going to have to gather your own washing water, though. And if they’re doing clean hand/dirty hand you should also respect it.