Thank you all so much! This helped! A few things I didn't even think about asking (behavior things). Thank you!!

start a list now. Keep it handy and add to it as you think of things.

Ask anything! Don't feel like it's stupid or assumed. I asked so many questions, potty questions (my son is not potty trained), lunchtime questions, activity questions, behavior questions, questions about other kids and other teachers, schedules and transportation.

If this is a transitionary and its meeting with the teacher he's leaving, I'd still ask how he's doing in those areas. My child acts differently at school then at home.

I would ask specific question about how they handle challenging behaviors. If your child has meltdowns, ask what they would do if he throws himself on the ground (or whatever the behavior is you might worry about).
Our biggest problem in kinder has definitely been keeping everyone on the same page with how behaviors are handled.