In a physical sense, yeah. But obviously there are other abstract factors of marriage such as the changed status under the law, as well as your changed social status. Subjectively, it can have enormous personal meaning, and likely does for most of the people who get married.
No. Marriage pre-dates religion and goes back as far as Mesopotamia. Religion already redefined marriage, if anything, pushing for gay marriage is taking back what never belonged to any 1 group of people to begin with. It's amazing that people make this argument when all it takes to disprove it is to actually look at the Wikipedia page.
Consenting adults should be allowed to marry if they want to. Be it incest, polygamy, gay or whatever. As long as everyone involved is over the age of consent for their state and consents to the marriage, the government should not have any say, one way or another.
That is still marriage I say kill marriage, stake it and put it in the sun like you would a mythical vampire and use simple private contracts once again when the vast majority don't marry the government must change policies. Without marriage there is no polygamy, no need for discrimination on consenting adults doing what they wish since you must be eighteen to enter into a contract. Lets then just end this archaic and outdated institution for all times.
if that happens it will happen for both heterosexuals, homosexuals and bisexuals at the same time, so for right now let work on equal rights, if later we choose to deny everyone that right, we can talk about that then, do not see Americans giving up that right without a fight though