By no means am I an expert in Search but I did want to make a note of one thing. A Boolean is represented by yes/no in a SharePoint list but in your search query string you should use true/false as the value. For example I had a published field that I wanted to append to the query string based on certain user selections. So I added "Published:true" via code. If you say add "Published:1" you will get the following error: "Your search cannot be completed because of a service error. Try your search again or contact your administrator for more information".

One final thing when you are mapping your properties be sure and select the type before clicking "Add Mapping". It isn't obvious at first but SharePoint is filtering the results based on the type.