Zoning is public records...contact the local town clerk office for a number to call.
Before you sign a contract, have an engineer inspect the house. You would not buy a used car without having a mechanic look at it.
Most older homes are "grandfathered" in terms of building codes.
If you need recommendations for a real estate attorney, mortgage broker or home inspector, please contact me off line at Gail@GailGladstone.com