You haven't gotten a whole lot of thoughtful replies, oddly. I think you raise a number of good questions. You also raise a number of bad questions, and a number of questions that imply that unless you can stop every school shooting with armed teachers, it's not worth doing.

But overall, it just seems like you're not interested in an answer to the question. You have experience, but you really can't use your experience to offer sensible ways to handle most of these topics?

For instance, if it's opt-in, with a firearms proficiency course, with firearms stored in several lockers and maintained by outside experts, and keys given to those teachers who are authorized to use them, almost all of your questions are answered and have reasonable answers.

It still might be a bad idea (I think it probably is a bad idea), but rather than a serious evaluation it seems more like strawmanning.