RE: The first one isn’t a problem for me. I suspect however a work around - like proving someone has been a dependent of the immigrant for the last 5 years - could easily be worked out.
Will the above be applicable for gays who were married in a country that recognized such unions?
Say, X is a gay spouse of Y in Country Z which recognizes gay marriage.... how can X prove that he is dependent on Y while living in country Z?
Yes, it absolutely would apply to gays, siblings, parents, and I suppose good friends. I don’t understand your question. They’d have to prove it the same way straight couples do.