Generally speaking (although it may depend on your state), residences are perfectly fine on commercial zoned land, they are just really rare. Local zoning can restrict certain uses, so it's good to confirm that it conforms. It's not unheard of for agents to miss this if the property looks like a residence, there is no reason to suspect it. The real problem is that lenders will not do residential loans on a property that is zoned commercial, no matter what is built on them. I'm not a lender, this is just how I understand it. You can ask the other side to extend escrow for another 30 days in order to try to get qualified for a commercial loan. Call some commercial lenders and see if you qualify. If so, just move forward if the seller is ok with extending escrow.
You aren't entitled to reimbursement for the services performed already (appraisal, inspections, etc) unless it's specified in your contract, which it probably isn't. If you choose to back out at this point, expect to eat those costs.