I believe it's 5 XP per 1000 points, but there are a lot of other things to keep track of, too.
Other than the dreadfully clunky interface, I really like the mansion mini-game (though "mini" is pushing it). If you want to dive into the details, you can find a lot of good information
here,
here, or
here.
As Shazba mentioned, Maya's dialog will change a little bit depending on the MC's choices. Even if the MC had sex with her in Ep 5, she was shocked that she couldn't take much of his infamous baseball bat despite being rather drunk. So it makes some sense she'd still be nervous about it.
Also, her main concern seems to be whether the MC likes what she does with him, which actually applies very well to this situation: she's worried he didn't enjoy it since he couldn't go "all the way" and was just being polite. Her concern is overdone, but it's understandable given that Maya is both very introverted and extremely uncertain about her sexuality at the moment (for several different reasons).
That said, I agree her actions make more sense if the MC went with Josy in Episode 5, which is a curious decision. I've always felt that, even though I prefer Josy's scene over all, following Maya was an easy call: Josy just got great news and is walking on clouds whereas Maya was feeling alone and vulnerable for obvious reasons. Maya's scenes in Episode 6 make me wonder if DPC expected us to choose Josy's path more often.