It is hard to say, but at least 10 to 20% as your potential buyers will be quite limited
2. We planned to rent this house out. Does renter normally check this information too?
You are supposed to release this information if you know it. Or you could get into trouble.
3. How much concern people normally will give regarding sex offender?
If they have a family, well, it is a great concern.
4. Should we still go with this house or back out?
If the price is good enough, then rent to a group of single and strong guys. Let's see who is afraid of whom.
Do not even try to rent to a family with young females.