Answer:
just tell her the truth , tell her she is a great freind and you would like the friendship to carry on , and let her know she will meet the right person some day and let her know that you will always be there for her as a friend only .
Answer:
Don't tell her unless she explicitly expresses interest in you first. But in the meantime, be clear that you will be her friend no matter what.
Answer:
show her that she can trust you. think of how hard it might be for her. it might even be hard for her to tell you. maybe you should sort of bring it up, not straight out, but in a way that makes her comfortable enough to open up to you. dont turn away from her when she needs you most. these are times that tell how strong the friendship between you two really is. be honest with her. btw, what does she do that makes you think she is gay?