A: 1. Limit your area to as small as possible then combine data after in database or something similar.
2. Yes, but you cant only use a zip code, you should use City, Zipcode or something similar.
3. You can also search by city but the area may be too large. You can also use districts or anything else that is inside of the city that the site will recognize stuff like "Soho" or using the Burroughs of New York, not just "New York, New York" "Queens, New York" works as an example.