If they can write a good covering email, have a few github repos, and some other indications that they might be smart/capable. I know from experience that it is easy to get interviews on that basis.

If you're talking about people who have no experience in the sense that they've never written a line of code, then no, obviously not. But professional experience and relevant qualifications are not necessary.

As with any job application, you need to have something going for you. It just doesn't have to be any of those two things.

No, you ask random people on LinkedIn like every recruiter does.