The health insurance would be done on a case by case basis that depends on the company the person works for. For instance, my health insurance can cover my "domestic partner" whether that partner is male or female. In fact because my vision insurance is better than what my girlfriend can get, she is on my insurance under this plan.

The immigration status is a bit more tricky. I hadn't thought in detail about that. I'm not sure what the solution there would be. Thanks for bringing that up, that's the first legitimate flaw that anyone has ever mentioned in regards to my marriage is a contract only idea.