There's no "standard" for insert sizes, every case is a little different. Legal size paper is all the same, 8.5 x 14. Any decent quality inkjet paper will be fine, there's no reall call for photo paper, as it all looks the same under the plastic case. Likewise, not all 4-disc cases are the same size, some are the same as a single case and some are fatter. You really have to have the cases in hand to know what you're doing.