> For [2] It's strange when I see these stats. Where I live in the US, 60-80% of high school teachers (depending on school) have advanced degrees (masters or higher). And that's also a weird stat to cite. What percentage of teachers with 5 years experience graduated in the bottom third? That would be a more important stat.
It's worth noting that the market for higher degrees for teachers is maybe not what people unfamiliar with it would expect. Plenty do get "real" higher degrees because they actually want to learn something, but there are strong incentives ($$$) for universities to offer fairly worthless higher degrees marketed toward working teachers, and many of them do.
Around here, at least, it's expected that a teacher will eventually get at least a master's. It's not expected that they'll choose a challenging program, or that they'll come out the other side substantially more knowledgable or capable at their job than they would have been without the course work. A master's from a top university puts you on the same pay scale as the guy or gal who went with State-U's-Cash-Cow-Teacher-Degree-Mill-Correspondence-Program—except that the school probably paid a much higher percentage of their costs than yours.