It's possible that the initial search that was uploaded did not contain the year or the year was in the wrong field.
Please send a ticket with the uploaded and exported files so we can look at them.
Dear Rayyan Users,
The moment a PDF file is added, a new filter box is added to the left panel "PDF full-text types" so you can filter on entries that have the PDF. This partially covers this request.
Dear Rayyan User,
Both RIS and BibTex formats can be exported by Mendeley and are accepted by Rayyan.
Thank you for your using Rayyan.