jQuery get all values with label and concatenate with a separator as a single string

Question 1

Something like this would get the labels and values

jQuery(document).ready(function($){
    $('input[name="add_custom_search"]').click(function(){
        var obj = {};
        $( ".searchdetails label").each(function(i, el) {
            obj[$(el).text()] = $(el).next().val();
        });
        $.ajax({
            url  : '/path/to/myurl.php',
            data : obj
        }).done(function(data) {
            console.log(data);
        }).fail(function(a,b,c) {
            console.log(a,b,c)
        });
    });
});

FIDDLE

But if you're going to just send it to the serverside, $('form').serialize() seems a lot easier.

Note that the form will submit and the page reload when you click the button unless you prevent the default behaviour, and that most times listening for the forms submit event is better than the submit buttons click event.

Question 2

change your jquery

 $(document).ready(function(){

    $('input[name^="add_custom_search"]').click(function(){
        $('[name="ElementNameHere"]').doStuff();
             var p1 = $('[name^="lblPostalCode"]').html();
             var p1det = $('[name^="Postal_Code"]').text();

             var c1 = $('[name^="lblCity"]').html();
             var c1det = $('[name^="City"]').text();

            alert(p1 + ':' + p1det);
            alert(c1 + ':' + c1det);
    });
});

and add name to your labels like this

    <div class="searchdetails">
        <label for="Postal_Code" name="lblPostalCode">Postal Code</label>
        <input type="text" name="Postal_Code" value=""/>

        <label for="City" name="lblCity">City</label>
        <input type="text" name="City" value=""/>       

        <input type="submit" name="add_custom_search">
    </div>