It depends a bit on your dialect. On the west coast of North America, "you guys" and likewise "guys" is probaly the most un-marked form of 2-nd person plural. In other places it's "y'all". I'm not sure if "you folks" is normal anywhere, but it's not that weird either. There's other forms to make it plural too, like adding on "people", but that's more coloquial.
As far as I know, "guys" isn't really gendered, with the exception of a few people on a linguistic crusade trying to make a point.