Integrate google 'place autocomplete address form' into my site's submission form

I have a website, built on ASP, that allows users to submit addresses that get put into an Access database. There are currently over 6,000 locations in the database. My problem is that users don't always put in the correct address information, and also they often submit duplicate listings. I'd like to integrate google's 'place autocomplete address form' into the current submission form on the site. This way, when site visitors submit addresses, they will automatically be properly formatted. The code then needs to put into the access database the proper address, city, state, zip, and country information. It also needs to automatically put in the latitude and longitude information into the proper fields in the database. When the user puts in an address, the code should check to see if this location was already submitted to the database. You tell me if you think it makes sense to search the database for duplicate locations based on the address, or the latitude/longitude information, or both. If the user put in a location that is detected to be a duplicate, the user needs to be warned right away (popup box or other method you fell appropriate) that the location was already in the database - this alert will have a link to that location's information in the database (I'll show you the code on my site to display information from a specific address), and ask the user to only continue entering information if they're sure they want to add duplicate information for the existing address.