phd - What should I ask my potential Ph.D advisor in advance, before actually signing a contract?

I'm currently applying for a Ph.D in Germany. Next week I'm sitting down with my potential Ph.D advisor to have a talk about the program.

Currently I'm collecting questions about things like

• teaching duties included?


• working hours


• what's the salary?


• vacation?


• budget for conferences?

I think I'm missing some important stuff.

My real question is: What should I ask my potential Ph.D advisor in advance, before actually signing a contract / starting?

(The question What questions should one ask to the former/current students of a professor before deciding whether to do PhD under him/her? is related, but I feel it doesn't fit my situation)