1. Heterosexual marriage doesn’t need a constitutional amendment in order to be so “enshrined,” so that doesn’t need to happen for non-heterosexual marriage, either. What does need to happen is this: gay people should not be subject to a different set of laws than straight people. We don’t need a constitutional amendment for gay marriage, because it’s the gay marriage bans which are already unconstitutional.
2. Speech rights would protect your right to say things I find offensive, but that doesn’t mean other social ostracism of you would be wrong, just as we socially ostracize racists, antisemites, etc. You would still have precisely the same rights as racist or antisemitic groups, you just do not have any reason to expect that there are no social consequences for exercising your speech rights.
3. We already regulate private business conduct under public accommodation statutes. I would be fine with adding sexual orientation discrimination to state laws which already include other classes of discrimination, and where such laws do not exist in some states, I’m fine with efforts to pass them.
4. Which LGBT issues do you mean, in a high school context? Do I think LGBT people have made significant contributions to our culture? Yes. Do I think we should study history, arts and the humanities in as unbiased a way as we can, even if I allow that it may not be perfect, in places? Yes. I do think as a society, we need better LGBT-specific history, but that’s a matter for historians. I don’t think at the hight school level this is anything special – I just think it’s history, so teach it as history.
5. Again, which policy? You need to be much more specific, here. There’s no monolithic “LGBTQ policy” as if that exists as a single notion. I don’t think it’s the national guard’s job to protect the public and enforce the law: that’s a police matter. But I do think there are instances where some crimes against LGBT persons are handled differently by law enforcement, again, because of their own biases, etc. about LGBT people. I don’t think that’s acceptable.
Edit: other answers have noted deployment of the national guard during the civil rights era, and I think that’s a valid example, but I don’t think we’re at the same point with regard to LGBT discrimination; if we ever got there, I might change my mind. I think calling it a police matter is sufficient because while violence against individual LGBT people certainly has happened, and is happening, it’s not happening on the same scale as the pushback against civil rights in the 1960s, say. That could change, but I don’t think it will.
6. Why are you focused on same-sex marriage, here? We already have foreign relations with countries which do all sorts of things I don’t think are acceptable; I don’t think the rights condition for women in Saudi Arabia is acceptable, just as one example, but we still have diplomatic relations with these countries. This is a tough issue for me, because I don’t have any clear answers, but marriage rights are among the least of my concerns here. I think there are much more pressing issues in many countries around the world, that we nevertheless maintain diplomatic relations with: violence against women, sexual slavery, and on and on and on. As an ideal question, I would like it if we had ways of bringing these countries into the 21st century on a whole range of issues, but I accept that that’s unlikely; I don’t think equal marriage is a compelling issue here, yet; there are other, much more pressing concerns.
What the Vatican does is of very little importance.
7. Speech rights would still apply to websites containing antigay speech. But again, that you have a right to post a web page that says, “God says homosexuality is an abomination” does not mean you have a right to no other social consequences for exercising your speech rights.