I would never talk about sex with my parents (aside from the "use protection" etc stuff.. I'd never discuss tactics!), and I cannot see why anyone would even contemplate chatting with the parents of the girl you're tapping.. that surely has no tact whatsoever.
However, I have no problem talking about it with friends of either sex, although when talking to girls I am probably more reserved with descriptions. It's not really a taboo at all in this country, especially as there seem to be far fewer no-sex-before-marriage style families, or heavily religious ones, come to think of it, in comparison with what I have heard of the USA.
As far as staying over, when I was underage (16), my parents wouldn't allow me to have girls stay over; I got the couch.
Now I'm older it's fine though.
I'm not sure about the situation with staying over at my girlfriend's, especially since I am her first so I don't know if she has had guys stay around before, but from what I have seen of her parents, they appear to like me and appreciate I'm not just one of the womanising players, so I hope they will have no problem with it.