No RNG there, some choices are stat dependent.
To change your equipment go to your room.
The wiki is pretty accurate.
Viewing post in Love & Sex : Second Base comments
yeah I figured out you have to be in your room to equip certain things but like the fact that it won't let me read a knowledge book. Also there should be more descriptions on certain things, like the icons for the girls' stats. I can figure out what the heart one means but like hand cuffs on one and male sign on the other? Domination and balance of heterosexuality?