I don't know what the legal answers are, but as a handicapped individual, I can tell you what works. An electric door that opens automatically with pressing a button is the best solution. The door should not have a high sill, making it difficult to get a wheelchair over. The door should be wide enough to get a wheelchair through easily. There are certainly organizations for the handicapped in your city who could advise you well on how to create a proper entrance, and would be very happy to do so.
