That's a very general question and to be honest, it just really depends on the person. I would say it wouldn't make a difference, to be honest; most people don't mind, and will date someone based on whether or not they like them and get on with them, rather than their sexuality.
Nothing like that! I don't understand this "bisexual" phobia! What's wrong in a person if that person is bisexual it's just another orientation. If you love a person you just love, no matter what is his/her orientation is.
Sadly, on average, yes. While many lesbians don't mind dating bisexual girls, there are the 'gold star' lesbians. They're typically pretty transphobic as well, saying that they don't want anyone who's had sex with a guy (or just male genitals in general) anywhere near them. They think they're superior because they haven't had sex with a guy, or who haven't had sex with a guy since coming out as non-straight. Again, while there are a lot of loving and accepting lesbians, there are definitely ones who are much less likely to date a bisexual girl.
No, when girls like each other, their orientation doesn't matter. Unless one of them has prejudice about another orientation, which unfortunately can happen sometimes but it's not that frequent, there's no obstacle for girls of different orientations to be together, if they like each other.