Grab loops. A couple short lengths of 7 or 8 mm perlon (climbers cord) make nice grab or hanging loops at each end. Make a loop, tie the two free ends together with an overhand knot, and shove the loop through the hole in the breast hook from inside, so the knot catches under the breast hook.
Seat cushion: in the past I've used some of the leftover canvas to cover the chunk of seat foam. This year I tried using some of the fabric dye to color the cushions - not a good idea, as it turned out; the dye ran when Matt and Peter tested their boat, so I had to remove the covers and wash them in hot water to resolve that problem. Hence the pinkish faded color in this photo.
Maker's mark: The little bronze tag that says Sarum Boats. Easy. Drop into the shallow hole and pin with two tiny brass brads.
Paddle note: While a skilled paddler, can pilot this boat with a single bladed canoe paddle, using the 'J-stroke', the boat is a joy to paddle with an extra long double bladed kayak paddle. There are some links to manufacturers on the Sarumboat blog. A little research on the Internet will also yield sources of plans for building your own, if you wanted to try that. This paddle will seem unusually long, compared to what you might find at the average EMS. Mine is 260 cm (102 inches). We made some here at school which are about 8' 4" (by the way, rubber drip rings are a good idea for your paddle shaft - they prevent some of the water picked up by the blades from running into the boat.)