I have two questions:
1. If I don't apply the "Incest patch" does it block me from Evelyn's route?
2. Is pregnancy available on the harem/bad ending route?
1. All the patch does is change Evelyn from the MC's sister to a friend, and alter her backstory and dark secret to fit them not being related. Revealing her dark secret involves the same steps (the form is the same, only the content differes), and you can still romance her in the same ways with the same risks (ie, she still leaves town if you tell her too soon, etc)
2. If you choose evil in the final confrontation with the villain, you are shown a very short epilogue where everyone is your mind controlled slave. No mention of pregnancy is made. To see the consequences of the MC having unprotected sex with characters, you must make the non-evil choice in the endgame.