Not really. But based on conversations I've had with folks who have worked on staffing such classes in schools, it is a known trade-off: A teacher who cannot answer all tech questions is better than a tech person who cannot teach. If someone exists who can do both, that is wonderful, but if you have to choose... choose a teacher.

Maybe some if you get lucky and find someone who's really into the subject, but it certainly wouldn't be a requirement because the people hiring for that position don't think that way. And I imagine the Venn diagram of people who know that and people who are willing to put up with how high school teachers get treated by The System (assuming we're talking about the US and not Finland) instead of getting a job in tech is pretty small.

From experience, no.

When you have to correct their code you know their ability.