i can answer that for you! pretty much getting the h-scenes is kind of a hassle. i haven't played the game in a bit, but if i remember you can get the H-scenes depending on how many keys you get. but you can always go to the grindy route and do the purification bit! i find it way easier to not only finish the game but also better scenes than the normal way. but if you do decide to go to the purification way to beat the game, depending where you purify her you will get a different scene
being in front of her is a BJ, behind her is reverse or normal cowgirl, and im pretty sure purifying her from the side is some other scene i dont really remember