Not currently. However, if you break up with Emily (not the other way around) to date Adriana, she will come back later and ask to start dating you again. She won't care if another woman is in the picture because she'll be desperate.
Plenty!
She goes for a lot of different dudes on the sub route. She can go for Josh, which is your bully, a black guy, a white guy etc. She however, never mentions the race of her date, or the IBWO or anything like that on the sub route, even when she's with a black guy.
As Antaraxes mentioned, it's on the sub route. However she will be a love interest on the dom route as well. Gina is more or less a fuck buddy.
Have you clicked the "You feel tired today..." option in the principal's office? During it's first event, you will discover the safe.