i don't know about officer, the lowest grade is around 700 i believe.. that's when mine changed from NCO to CO.. and it's still at 2LT, which would make sense since if the ranking system follows the normal COC :?
i googled it, but i believe it's a plugin/addon for the PHPBB system. and i don't really care that much, so i only skimmed through the first page of hits with no pleasing results