If your Mom is dropping hints, and seems like she would be supportive I'd tell her. The support from someone you love is amazing. You of course know your Mom but my Mom knows and is supportive of me.
As for your friend... Again be sure of your intel, but telling them you dress is a great opener. Hopefully they will open up, but depending on where they are (how comfortable/confident in who they are) they may not open up right away.
Risk vs reward thing, but I agree that having a friend to share all of you with is worth the risk.