SEARCH URL QUERY OR placeholder ???

Right I don't know which name to give to my question but you will understand me and I hope help me.

Because my (cgi page) don't have the option to keep the search query in the search result template page I need your help.

Here is an example with AutoTrader.co.uk
When you click this link you go to the result page which keep the search query - in this link we search for - ALFA ROMEO 145 BETWEEN 1000 AND 5000 AND POST CODE IS w13 0np
URL

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For now I can do it using javascript like here:
URL

with text field - as you can see the result template parse the word "Sydney" in the search box.

I REALLY NEED YOUR HELP GUYS, I WANT TO FIND A WAY TO DO THE FIRST EXAMPLE - WITH NOT ONLY TEXT FIELD BUT - DROPDOWN, CHECKBOX...ETC.


Thanks a lot.