The short answer is that strip built boats can take on just about any shape, as the individual strips are small and easy to bend. You could, with a little bit of effort, make a perfect sphere out of wood strips - which would be difficult indeed with plywood!
That being said, I've seen some intricate shaped kayaks built out of plywood. Of course, that was plywood cut into shaped planks. Kind of like strips . . . .

Two singles beats a double, imo. There's a reason doubles are called "divorce boats."

For a kids kayak, you might check out Tom Yost's Sea Flea or Sea Pup designs. Built as a wooden frame, non-folding, boat, these are inexpensive and very quick to build.
http://yostwerks.com/SeaFlea1.html

Have fun!
Dave

: I am a former resident of glastonbury, grew up near the old cider mill, but i
: have decided to build a kayak with my 12 year old son. i have no
: experience other than scratch built wooden ship models. I have come to
: love Nicks designs but wonder why the strip kayaks seem to have a nore
: graceful curve and shape than the hybrids or other construction
: techniques. Is it better to have 2 singles or one double.