Ask HN: What questions should a student joining a startup ask?

Hello. I am an upperclassmen in one of the top CS programs in the US. I have been offered an opportunity by two professors to work with their medical technology startup. It's still in the very early stages. There are two founders, although they've worked with a number of other people in some capacity. They have a core product that does analysis of medical data, and it seems like their main focus now is polishing it and putting it into a user-friendly package. They want a web app in Python/Django, which they don't know too much about but I have a fair bit of experience with. I'm somewhat new to the startup world, and I'm not sure what questions I should be asking to assess what I'm getting in to. (Aside from the obvious, like "what is the product" and "how will you make money".) Any advice? Also, I'm not sure what I should ask for as compensation. Course credit as an independent study? Cash? Equity? Any suggestions here? I'll be a student for 1.5 more years, so it's not like I'm risking my personal financial comfort with this startup or anything. If it goes nowhere it's not really that big a loss to me.