The endplates are thin hardwood pieces that are attached with dowels to the gunwhales and stems in our case. You don’t have to have them but they help make a nice continuous line along the deck. They also lock in the gunwhales and make your kayak more durable.
Kerfing is the art of being patient and make small, shallow cuts with your saw and then tidy everything up with a chisel and file. It’s worth the time and effort you put in!