I only answered the first one because it is legal in other country's. They have laws governing all those situations. A little more complicated legally is not an excuse to deny equality under the law, period. I mean look at our tax laws now for an example.
First, It would take a significant rework of our laws regarding marriage, from tax code to court precedence and onwards. "Other countries" having it does not in any way negate the difficulty and amount of time spent in changing THIS countries laws. The vast majority of laws would require a mere tweaking to go from allowing only opposite sex to allowing any two people. An entire rework would be needed to allow for joining of 3 or more people. Minor rewrites for something that is discriminating as a Middle Tier category, sex, is far less of an argument against EPC than major rewrites applying to discrimination that would be questionable if it even registered as a group that could be considered under the lowest tier.
Secondly, yes...the difficulties in changing a law is certainly a feasible argument for discriminating against people under the law. Especially something, such as "number of people", which would fall under the least strict tier of the EPC if it would even reach that level. It is a "rational" basis in suggesting this discrimination serves a legitimate government interest, that of spending time and money on issues at a reasonable level of importance compared to cost. Seeing as how there is no strict constitutional protection towards "Numbers of people" that can enter into a government, the amount of time and effort to go into reworking an entire section of our legal, tax, and court systems to accommodate this is not reasonable. And such is all that would be required to constitutionally allow such discrimination.
Thirdly, this is not even toughing upon the other potential issues which I'm sure others who have studied those things more would be better apt to speak on, for example regarding family units and other such matters.
Now on another note with regards to your tactics here.Seriously, you're Colbert act is rather worthless and tired and since you don't even throw random references to bears into it, it doesn't even have worth as being at least a mild form of entertainment. Your attempts to, poorly, mimic the criticisms of your own critics into a debate that is similar...but yet still remarkably different as well...are so transparently poor that you may as well be sitting around with a fisher-price toy trying to shove a square peg into a round hole. The entire thing is made even more redundant since most of the arguments which people throw against your attempts of pushing your religion through the law are in no way shape or form the same arguments I actually make, and as thus ring all the more hollow.
Your "I don't give a **** what the constitution says, all I care about is the bible and god and my interpretation of it which is infallible and thus by god the government should do what I want it to do" shtick at least came off as sincere and honest and allowed you to passionately defend it, as ridiculous as I and others may view it. At least you could put together an actual argument for it based on your actual thoughts that, while perhaps made no sense legally or constitutionally, at least made sense from the point you were arguing from. This? This is just ridiculous attempts at parroting someone elses argument in an attempt to be ironic or to show how poorly their argument is, when in reality its just showing how poor you are at this form of debating tactic while shedding absolutely no negative light upon the side you're hoping to make look bad in this.
Seriously, stop. Stick to what you actually believe is, for bringer of truthiness, you are not.