If you aren't someone who discusses previous relationships/sexual experiences before getting in to a relationship with someone then i don't think it's fair to now judge him on this.
ME personally, i'm upfront when things are looking like there's attraction significant enough for a possible relationship. I have personal beliefs about sex, i couldn't be with someone who has had casual sex, to me it is about love and i believe in only sleeping with someone you have genuine strong feelings for and want to spend your life with. If someone doesn't want to discuss their previous sexual history, then they're not the person for me. If we have different feelings about when it is appropriate to have sex with someone, they aren't the person for me.
As for would i date somebody bisexual, no, i wouldn't. I don't agree with anal sex, and whilst i know not every man who has a same sex relationship engages in anal sex, i don't want to ever be put in a position where it's something they will potentially ask for, due to an ex threatening me with tying me up and anally raping me.
I am admittedly also insecure about me not being good enough due to past emotional abuse by same said ex, i don't want to have to worry and be irrationally insecure not just about their female friends but their male ones also that they could leave me for.