Yes, currently the lewd scenes are more like quick encounters which I tried to implement somewhat naturally over the duration of the game. Some characters are more prone to being straight forward while others are going to get what they want through teasing, while some of them again are totally different and have a somewhat "normal" relationship progression. Like a little bit of everything for everyone. Having Lucy teasing the player wouldn't fit and teasing isn't a big part of any character, just specific ones. You'll have to "earn" some lewd scenes for sure, but there is also the question what earning means. If you play the story normally without having to take any difficult choices on the way, is it still earned when you get the girl you wanted from the beginning? I do have plans for every character and you'll see them approaching the player or the other way around, in different ways! Nothing is written in stone yet, but those are my guidelines at least. :)
I can definitely make a list with the songs at some point. They're taken from everywhere basically, online no-copyright sounds over attribution sounds which you can find in the credits up to paid ones from different sites.
Hope that I could answer your questions!