There are no pregnancies in Nergal's version. Xalenda's mod has the closest thing, but there are no sprite/image/story changes. It's mostly lip service, but still kind of interesting.
As far as the endings I don't believe there is that much of a difference between any of them. The game is still playable after you finish it. There is a final scene, which is, like the others, repeatable. Depending on your choice(s), the scene differs in dialogue and sexual position. Other than that final scene, I don't believe the outcome at the end changes anything in the Overworld.
Being Good/Bad/Blackmail changes the dialogue between the MC and his partner(s). You can see what they'll say by going to each character's Dialogue folder. Most of them will have something like Purity/Corrupt/Blackmail, BJ/Ride/Park/School/Paymeon, etc. Heck, you can even tweak some of it if you want.
Also, you can enter the cheat codes on MC's computer to unlock all the scenes and another code to either fully Purity/Corrupt the women and play any scene you may want that way. Unfortunately, the Blackmail options, Donna's scenes and some of the fun before the scene and after scene dialogue you'll miss out on.
