JSON Seach

I am trying to create a search query for either the YearBuilt (yachts.theskywatergroup.com/yatco_data_feeds/datafeed_customer/query2.php) or LocationState a Vessel is located in (yachts.theskywatergroup.com/yatco_data_feeds/datafeed_customer/query3.php.) 

See attached files. I can only get the full return of the URI.

I am not fluent in PHP coding as I am more involved in web design, graphics, emarketing, etc., but want to learn this for one of my friend's who is a Yacht broker.

Part of the example response data from the "Search" URI is below.

A few questions as this is new to me -

1 - What are the numbers and "String content" in JSON?

2 - Can $_Get('City') be a request from a form?

3 - Is it my code in the attached files or is there something else I need from the providing Dataservice?

{
    "PageCount":"2147483647,

    "RecordCount":2147483647,

    "Vessels":[(
        "AskingPriceFormatted":"String content",
        "City":"String content",
        "VesselID":2147483647,

        "YearBuilt":2147483647

    )]
}