You may do pretty much anything to the interior of the home. The exterior must meet qualified guidelines provided by the Amherst Historical Commission. The entire Village is on the National Historic Register. You will have to have new windows approved, you may not put vinyl siding up etc. You will need to present your plans to the Committee at their monthly meeting. Pretty much anything that can be seen from the street is regulated. This is done to preserve the look and feel of the Village and it's authenticity. It also protects the resale value of all of the homes in the village in this manner.
Please feel free to let me know if you have any other questions, I would be happy to guide you in your purchasing process.