Where you could say "guys are obsessed with sex". I don't see it that way whatsoever. It's all relative, I see girls as tending to be sexually fridgid and guys as being normal.
what age do you start thinking about/doing sexual things?
Very young.. From about 8-9 I thought about it naively. From 12 was when I started "doing" sexual things.
how often do you think about sex/sex-related things?
Every time I see a nice face/shape/cleavage/ass on the street/tv/magazine. If I smell a nice perfume or hear a girl with a scottish accent.. Most of the time I require a trigger, but it takes very little.
how often do you get turned on?
Almost everytime I think of sex, which would be a lot. If by turned on you mean erection, the two don't always go together (unless you need them to, and even then some people still have probs)
how often do you masterbate?
On average? Twice daily.. I'm not in a relationship
when starting a relationship, are you keen to become sexually active quickly, No, not really. I prefer to build up to things. More fun that way IMO. It also depends on what you mean by quickly. If I'm a month into a relationship I expect to be getting laid (at 22 I mean come on).
is it something very important to you in a relationship with a girl? Even though it's not something I'd like to rush into it is very important. Physical intimacy is a large chunk of a relationship, otherwise you might as well just be brother and sister.