It may not be extremely common, or at least not yet or at this current and particular time, but, yes, it is definitely O.K.
Absolutely! Some guys can totally rock that pink!
In some places, it's not considered socially appropriate. I have a pink cell phone (I got it from my sister, and haven't gotten the money to buy a new case) and I get people asking me, "You still have that pink phone case?" all the time.