Index the Osclass car attributes of an ad for search queries

Hello, i use osclass 3.6.1 with Responsive One theme Osclass ( ) Freelancer must have experience with osclass and its code. what I want: 1- To index the car attributes of an ad for search queries? This way, if an ad has an attribute that matches the user query, it can be displayed on the search results along with the other ads that match in title/description. here are the car attributes (fields) that i want to index to the search queries: Fuel type, Car Made. example: if a user types in (Mercedes diesel) into the search box, all ads corresponding to this query should appear. 2 - Add "Fuel type" list dropdown into the car search window, so user can narrow down their search by choosing Fuel engine type (Diesel, Essence, GPL or Autre). 3- Add "Min year" and "Max year" into the car search window, so user can narrow down their search by selecting Min. year and Max. year. 4- Add "Mileage From" and "Mileage From" into the car search window as follow (From: Mileage min-value to: Mileage max-value )