Redshirts is a d20 sci-fi game that is based off of the Pathfinder RPG.
...And we assume that you have at least a basic knowledge of said game.
Unless otherwise specified, the standard pathfinder rules should be used. An entire new set of classes and typical equipment will be provided for the setting, but many feats, traits, and other items remain unchanged and will still be available from the Pathfinder RPG core rules.
Use some common sense in this - just because a shovel isn't listed in the equipment chapter, doesn't mean that shovels don't exist. This section also assumes a decent working knowledge of the Pathfinder RPG system.
Later on I may try to write a completely separate set of rules so that Redshirts functions as a self-contained unit. That probably won't happen for a long time, though.