I disagree with your checklist. Assuming you are interviewing for a very early employee (first 10 at most), then all those are technical issues that you will be

I disagree with your checklist. Assuming you are interviewing for a very early employee (first 10 at most), then all those are technical issues that you will be able to fix. That's not a problem, that's your job and you are good at it. I would worry a lot more about the business itself. Does it make sense? Do you see a credible path to paying customers? And the most important of all: are the founders the right people to grow and lead this thing? Could be experience or passion (ideally they should score high on both).