A fair number of guys (me included) like bobs. I only know one guy who really likes shorter then that.
Its absolutely masculine to have shorter hair. You will notice that the majority of women who people say 'pull off' having really short hair are waifs. They are really delicate and 'feminine' not even in a curvy but in a 'small and weak' way so even a tougher more masculine haircut leaves them -overall- seeming very delicate. The guy I know who likes pixie cuts also likes women who are tiny.
Generally I'd say the bigger a woman is, the longer the hair she needs before guys will start thinking 'eehhhhh'. And its not simply a 'smaller is better' thing - its that the overall balance of their frame and hair leaving a final impression.
I'll also note that shorter then bob length is a bad idea for women who don't wear makeup frequently. If you don't want to look like a man, man-short hair is your one 'non-feminine' thing that everything else needs to offset.
It depends on how the rest of the woman looks like. Some women can look better with short hair. The hair in your profile picture looks very good. You just have to experiment and see whether short hair suits you or not. And don't forget to style it. Just because it's short doesn't mean you don't have to take care of it.
I think it depends on how short and the style. Honestly, I prefer medium to long hair, the type that's long enough to put in a bun or pony tail.
My honest opinion though? You shouldn't be worried about what other people think. This is a personal preference. While I like longer hair, a guy that comments after me could love it. Plus, hair is always temporary. I.E. while you have short hair now, only 2 months from now you'll be back to medium at least.