Are the bearings bad? i.e. is there any perceived play in them when you wiggle side-toside, top-to-bottom? If not then I wouldn't touch them. To take tem off you will need to remove the hub-cap and there will be a nut, maybe a cotter pin too, holding the hub on.
I'm not sure about the maker of the rear hub/bearings, but I would have to see one, off the car to tell who makes it and if it is a serviceable unit or if it is a throw-away (you buy a new hub-bearing unit and and retorque the nut).
