Are there anyone who could suggest literature, web sites and other
sources
of high quality information that could direct me to the theory and
mechanics of sail, its materials, how to calculate geometries, various
design principles and ideas. Also, learning the craftmanship would be
very
interesting.

I did an apprenticeship (way back when that was possible to do) with
Ratsey-Lapthorn Sailmakers and built sails for a living for a very short
while (not an easy business to make money, IMHO). Every book I've seen on
the topic is way out of date. Every major loft (and maybe every loft by
now) uses some sort of computer application to design, and often, to cut the
panels for a sail. The fine art of sailmaking has become the fine art of
computer design and a (usually low paid) seamstress. The software they use
is proprietary and the information is strictly protected. I've seen some
free software on the internet in the past, try a google search for "sail
design" and you may find something worthwhile.

On the "theory" of sail design, look for books by "Marchaj". He was the
leading theorist when I was into that kind of thing. The reading is pretty
heavy duty though.

Sailrite is the only company I know of that still offers sailmaking kits,
and they have their own books on the subject, no idea if they're worth
getting though. They also sell some very reasonably priced sewing machines
that will work nicely for a project like this.

I'm assuming you plan on doing this for the challenge and education it will
give you. If you're trying to save money, you'd be much better off buying
pre-made sails.

Hope this helps,

Paul