why don'tt you just add her. and if she asks who you are then tell her how you know her. i mean its not like she will act like your weird and laugh about it with her friends or tell everyone a weirdo added her. im not saying your weird but its just an add. so go for it
yeah. you should call. if a guy gives you his number that usually means he likes you. usually a guy wouldnt just give anyone his number just to be nice. call him