you only think about your studying and your interested thing that you like, and do never give a care to him ,only treat him like bro or you can only care about him, dont attract him very much or any thing that let him think just for a moment that yup you love him and you will die for him , he will let you and go, trust me and do what i said :)
That would depend on the girl. There are some that right away you can tell and some that can hide it really well. If you really like her try to get close to her as a friend. Get to know her on what she thinks, feels, and expression. or you can straightout ask her what she thinks of you.