This definitely sounds like something that you could do with DataAssist, but the dynamic dropdowns part would need to handled with our Dynamic Dropdowns tool. Essentially this is the same as a search like this that would have text fields. The only difference is that after you have configured the search and results page you would replace your text fields with these dynamic dropdowns that have the same name. This would give you the same result as if you had entered the exact same values into your text fields.
So the first step in this is getting the search and results set up and working. Once you do that you can add in a couple of recordsets then the select lists and start applying Dynamic Dropdowns to them.