So If I scan my film how many DPI should I scan it at? 600dpi? I scan my film at 2700dpi 24bit 3702X2514 but depending on the size I choose the dpi would vary i.e. a 5R would have a higher DPI than a 8R (300Dpi).
Just scan the highest you could afford to store and process. You don't have to scan at lower resolution if you want to make smaller prints (unless you don't intend ever to make big prints from the scan).
Anyway, you need to scan at ~1600DPI if you want to print 5R at 300DPI.