If 1 is true, then marriage should no longer have special status in our laws. So, instead of trying to get the government to recognize gay marriage, the special rights for marriage should be largely done away with, or made dependent on actually having children.
For 2 I am wrong and uninformed then. If it is only a state by state issue and it is supported by the majority of a state, then I don't see a problem.
2. I wish that you would define what you mean by "contrary to the American experiment." No one is advocating gay marriage for all states. Many people are demanding their own state government recognize civil marriage as distinct from religious marriage, and that all citizens have equal rights to civil marriage.