Screw spacing should be 6" o.c. at the boundaries and 12" o.c. in the field, assuming an unblocked diaphragm. For blocked diaphragms increase the numbers of screws by 15%.
Typically two screws at each deck board/joist intersection, approximately 300-400 screws per 100 square feet depending on joist spacing.
Approximately 34 screws per 4x8 sheet.