What model Shrike did you choose?
Shrike Too at 108%.

What modifications, if any, did you make to the design described in the Build Manual?
Model is shrike too, 8% enlarged with keyhole cockpit. Hatch covers are cut straight from a deck, epoxy was replaced with polyester resin, entire boat is from 4 mm okoume plywood, without fiberglass coat (only gunwales, chines and keel were taped) and without skeg.

What is the weight of the finished kayak?
Weight of completed kayak is 20.5 kgs.

How does the kayak perform on the water?
First launch went well, and i´m still alive:-), big surprise for me was great stability.