Hey there.
You can definitely use the template without any external inventory system Pirate’s system is great, and you can implement it into the MSGT if you want, however, the MSGT comes complete with it’s own inventory system, set up with weapons, armor, linked to the hunger system, thirst system, etc. (so that when you use items the correct thing happens) and such, so I would recommend taking a look at the included inventory before you try to implement his system as well.
As for stats - the equipment, by default, has an armor rating (defence) and will soon be getting a temperature alteration rating. But everything is made with the intent to be expanded upon, so it is incredibly easy to add extra stats to it if you wanted to as well. Hope that satisfactorily answers your questions Always happy to offer help with any expansion (within reason) as well!