The contract that the interviewer has may not look anything like the one you are going to get. The only contract that matters is the one you sign.

Every company will negotiate the contract with you and they will frequently be happy to negotiate other things than just your bare salary. There might be things that you care more than others and the company will be happy to provide you with.

A lot of people treat the contract as a formality. Don't. The contract is there for you to feel safe and for the company to get what they need, too. This is the actual agreement between you, everything you had before should lead to writing down what you figured out in form of a contract.

As to asking for reasons of previous person leaving, I think turnover rate is definitely better question. One that can be followed with an actual discussion about the reasons for this or the actions that are being implemented, etc.

Even if a potential teammate has an overly restrictive IP clause, in my experience a lot of companies are genuinely using boilerplate, never thought about it much, and are happy to redline to "Company's IP if on company time / company equipment / directed by company". I don't think it's inappropriate to bring it up with a manager, but I wouldn't trust any answer until you get to contract negotiation.