: 1. Is it necessary to have continuous
: strips? I have the capacity to run no more than a 12' plank through my
: tablesaw and the kayak will probably be 17'

It is quite possible (and practical) to scarf shorter pieces together. I created a "miter box" specifically to cut scarfs in the strips I used. I glued up the first couple for the shear before starting to strip the kayak. From that point on, I glued the joints as I placed the strips in place on the forms.

: 2. 4/4 lumber will result in 3/4" strips - everything I've read
: indicates that 5/8 strips are more pliable. Is this correct?

I've used both 3/4" and 5/8" strips. Bead & cove on the 3/4 essentially reduces it's width and adds flexibility, but the 5/8 strips are certainly easier to work with if you have a significant arc.