Customization of search engine of a Wordpress template

Hi, I need to customize the search engine in the sidebar of a real estate website that was created using the Elegant Estate theme. Consequently, the freelance should know and modify the template and its categories, ePanel, ET Settings, etc. .. This is the website [login to view URL] and currently the site has these four boxes: 1) Types of property 2) City 3) Prices 4) Square meters These are the two customization that it needs: 1) Each drop-down box must include the ability for the user to select all the fields inside the box with the text "ALL". 2) Create a single "Search" button (instead of 4) in the bottom of the 4 boxes to allow the user to make a multiple choices simultaneously using the criteria of all four fields (see the attached file of final result). Please, also let me know the delivery time. Thanks to all.