Thank you very much for your interest. I try to reply your questions:

Describe the current deck construction.
It was made in 1978, probably with very high standards (Nautor's,
Finland), fastened with screws and, I think, probably glued.
What is the hull material?
Fiberglass
What is the observed faults with the deck now?
Several of the screws stick out of the surface, few planks are not well
fixed to the deck and water seeps under, the caulking is missing in
several parts. The worst part are amidship around the chainplates.
Overall I believe that the deck should be redone entirely sooner or
later but I believe also that with some work I could wait, say, 3-4
years before a major work and a major investment.
How thick is the teak planking?
It is quite thick: probably around 12-14mm
How wide are the planks?
around 43mm
What caulking material has been used?
I don't know

If you are interested, please look at the pictures posted in this page
http://g24met.phys.uniroma1.it/cache

Regards
Daniel