I think that adding in Dynamic Dropdowns will be the final part of this. In your current search and results setup are you able to enter the values and get back the correct result? You should have the search all setup to search on the date like you have described first. Once you can verify that you are able to enter the desired search term into a text field and get back the correct result then you would be ready to make the inputs select lists, and use Dynamic Dropdowns.
Post back and let us know if the page is working correctly now for you. Once it is we can discuss how to add in the select lists and use Dynamic Dropdowns if it is necessary.