Girls Only!!!!!!!!!!!

It doesn't exactly means he likes you, he might just be flirting with you or even trying to annoy you, because if he liked you he might not try to make it THAT obvious by calling you baby ...At least thats what I think

That depends all on what your type is if he's it smile and say "hey". If he's not don't smile and simply say "hello" he is way bellow you don't smile don't do anything more then look at him with a look of something like 'can i help you?' if he is out of your league in a good way, congrats, smile flirtfully and say "~hi~".
Good luck even though you shouldn't need it.

I don't really think it means anything. A lot of guys tend to walk up to a girl and say "Hey, baby" in a joking matter, nothing as serious as liking her. I'm guessing that he was just simply saying hi in his own little way.

I don't think he said it because he likes you ..

It's either in a funny matter OR he's trying make another girl (most likely his ex) jealous.

Every day random guys come up to me and say 'will you go out with me?' or 'your so beautiful' as a joke and it really annoys me. I think he was probably joking or he liked you before and he's trying to cover it up:)