Google Maps API, search user address against DB, display close results with details

Background: Currently a lot of POI (points of interest) are stored on google maps that only we have access to. These POIs are regularly backed up in .KML files and have detailed information that is really only of interest to us but some information would be good for customers to search on. It would be good if a potential customer could enter their address into an online form and press search. The results could be displayed in one of two different methods. 1. on a google maps style page with POIs represented as pins, dots or blobs, or 2. as a list sorted by closest distance first with information read from the .KML (or the google maps data). There are certain boundaries where addresses are out of bounds, the system needs to advise them of this in the results. Currently these areas are shaded areas within the google maps app and saved in the .KML as a polygon. Requirements: 1. Solution must be able to be embedded into existing website that utilises SiteBuilder 2. User must be able to fill in form with their street address. 3. Solution must convert to a GPS or GIS style format and search for POI (points of interest) within a 500m radius and 1000m radius (user selectable). 4. POI within radius are to be retrieved and the header information is to be displayed in a results window along with the distance to that POI. 5. Every time a user enters an address, an email is forwarded to a specified address with the searched address and the results displayed. 6. Solution must advise user if they are in a zone that is out of bounds. 7. ‎only a limited number of searches can be done from the same ip address per session/hour. A notification can be displayed to the user. If the solution is easier to be stored in an SQL database this can be an option . Currently there are only about 250 entries in the .KML file (or database) but an import of several thousand is planned as stage two. These will be imported from an Access relational database. We are happy to discuss any options or suggestions you may have to better store, search, display results from the data lists.