> To saw plywood parts to build stitch and glue kayak for plans, what saw is
> best?

I think a skil-saw with a thin blade on it works best for cutting panels. It would be too difficult to wrestle the sheets across a band saw. A jigsaw works well, too, but the skilsaw leaves a smoother curve. You want to leave a little for planing to final dimension anyway.

> Band saw? If so: How large to enable curves?

I use the band saw on large, thick curved peices, such as deckbeams cut from 2x or 1x material. I am lucky to have a fairly well equipped shop, and have found a scroll saw to be ideal for cutting small plywood parts like bulkheads, foot braces, etc... I'd highly recommend it, the shapes you can make are limitless.

> Can same saw be used to saw strips for strip-built kayak, or is a larger
> saw needed for this job?

Bandsaw vs tablesaw is an ongoing debate for this. Bandsaw wastes a little less material but tablesaw leaves a smoother finish, no planer needed. My preference is a table saw with a thin-kerf skilsaw blade in it. RAS will work if well set up with infeed and outfeed tables.

> I really wood not like to buy the wrong tools, or to have buying two if
> one is enough...

Buy the best you can afford, you wont regret it.
> Jan Gunnar