I would like to address just that one issue. I'm not sure how to deal with the issue of halakhic arguements directed at people who do not feel that halakha is not obligatory. If you are not going to argue against a chesseburger from a halakhic perspective, then I agree you should not argue about homosexuality from a halakhic perspective. There is no halakha that says a woman must be a virgin at the time of her wedding. Those of us who follow halakha do.
First part is a bit more complicated, second part is simply wrong.
An ejaculation renders a man Tameh with Tumat Keri. I have no proper English translation for the above. It is correct that the way to remove this Tumah is with a dunk in the Mikveh. You cannot eat things like meat from a sacrifice, if you are a Cohen you cannot eat Terumah, non of which is applicable today. So there is no compelling reason to remove this state of Tumah.