One of the NYCC round table interviews with Tom and David S. Goyer - the one mentioning polyamorous sex - has been transcribed by Just Press Play.com and posted on their website. Read it in full on that site.
Q: I studied Da Vinci in college, but I didn't know most of the things that I've learned from the show. What's the most surprising thing about him that you've learned from doing this?
Tom Riley: Probably his anatomy dissection, of course, and when I saw an exhibition of his that showed how deep into anatomy he went. At the very end, there was a piece saying that it was lost to history but if it had come out, he'd have been the greatest anatomist that ever lived. You think, how is that just a hobby? How do you have that as a hobby and be the greatest that anyone had ever known? But also, and it's the strangest, the double-edged sword of the part, but people have such expectations of who he was and yet you want to do justice to the stuff that you found out about him in his twenties that no one really knows.
David S. Goyer: There's a lot of misinformation about him-
Tom Riley: Yeah, there is.