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If you do talk to this teacher, I think you should emphasize the importance of answering the kids' questions each week. You could do this by suggesting before class that the questions are really important to the kids, reminding her to reserve enough time. Or, if you're in the classroom, perhaps you could point out, "Hey, it's about time for the questions." If she is forced to answer the questions, this will ensure that at least some of the class time is not spent on her sex life. (She might make the questions about her, but at least she's addressing their concerns.)
As for her boundary issues, that's more difficult. It sounds like she has an inappropriate desire for her students to see her as a sexual person -- it could be coming from a creepy place, or from an honest belief that if she talks to the students like peers, they will be more willing to take her seriously.
The most important thing is to watch the reaction of the students: If the students seem uncomfortable, her method is not working, and for their sake she should be reigned in. If her "inappropriate" disclosures prompt the students to be more honest about their own feelings, then maybe it's not so bad. You and the other teachers can represent adult/authority figures, while she fills a different role.
When I was a teenager, I had strong connections with adult mentors who treated me, perhaps inappropriately, like a peer. Those relationships helped me, because I was the type of kid who resented authority and hated being "taught" like a child. Getting to know them as friends allowed me to learn from them, and I became a more stable, productive person because of their example. But it worked because while these adults were candid with me, they weren't creepy. They never would have told me they had a fantasy about me, or about anyone my age.
Try to figure out how the students feel about her. If they think she's cool, it might be an okay situation. If she makes them uncomfortable, it's time to step in. And either way, make sure she gets to the questions -- it's so hard for kids to write them down, even anonymously. Make sure they are rewarded with respectful answers.