I would not agree it is appropriate in a public school setting to have a course which is exclusive to any religious text. That would be appropriate at the college level, but not in a public school.
Again, I disagree. Students should offer electives that are of interest to students. I should be able to take an art elective on painting without having it include computer art. Or, I should be able to take German without also having to learn Spanish. Keep in mind, I live in an area with two large high schools, which from sheer volume can offer electives that can specialize. For example, the music electives include choir, orchestra, marching band, jazz band, and guitar. Art is broken into general art, painting, ceramics, photo art, and I forget the other.
I can imagine a very small high school would have to settle for offering music or art and be glad to have both. If someone, because of background and culture, wants to learn more about the Bible in a public school setting, I don't think that student should be told, "You have to learn the Koran, too" anymore than a Spanish student should be told, "You have to learn French as well." Let students study what interests them (when it comes to electives). If you are speaking of small schools, then I agree, their electives may have to be broader in scope in order to offer anything at all.