I think it's both a calling and a choice, but perhaps that's part of a wider debate between determinism and free will.
Yes, I consider celibacy a valid lifestyle, though from my view, it seems to be very rare and people think you're nuts!
I'm still a little undecided about whether I'd like to get married. Perhaps if I met the right woman, but I think she'd have to be near perfect to tempt me away from my commitment to celibacy! But I can't deny the dream of finding a girl who I love and who loves me back is a very sweet one, though I suspect the desire is more abstract than real. In reality I know marriage wouldn't be easy. I think my best hope is perhaps to seek a close platonic substitute; a dear friend to go through life with. I think that'd be sufficient for me.