On #1, you can, there just aren't any laptops with exactly 13" screens in the db, so nothing is returned (the closest are 13.3" and 12.5"). Try 13.3" - 13.3" and you get results. For marketing purposes manufacturers often round down to a whole number, e.g. Apple's 11.6" MacBook Air model is marketed as 11", and their 13.3" model is marketed as 13".