Next level relationship.. mmh, I'm not sure about it. Isn't Lily's cheating part what makes her "relationship" with Fred interesting? She cheats on her husband (whatever his name was again), because she is sexual unsatisfied and Fred is capable of willing this cap. Therefor, I see their relationship as a casual "friend with benefit". So, I'm not sure if they should become a couple in secret. Why not an open marriage were she stays with her husband (was his name Nick?), who knows that she fucks his dad too?
I think this is due to P & P's laziness.

Well, domination doesn't always need to be "being in charge/control", maybe she likes being pound hard and the best way getting it is the doggy position. However, yeah more different positions would be nice.
You should be grateful that people take their personal time (and hoster space) to provide a compressed version, otherwise you could do it yourself.
Start doing one, if you want a Ren'Py remake.