Just a few thoughts on the thermal protection question...

First rule of thumb - if you couldn't swim comfortably in the water for
however long it takes to re-enter the boat or get ashore, you need some sort
of thermal protection.

Wet Suits - we bought farmer john suits during our first season of kayaking,
and used them for a couple of years - well, sort of...in fact, we didn't use
them as much as we should have, for the following reasons:
- Hard to don and shed.
- Tended to be hot in the boat given much exertion.
- Tended to be cold if sweaty when exercise stopped.
- Tended to chafe.
- Very cold if exposed to wind when wet.

Dry Suits - so, two years ago, we finally bit the bullet, and spent about
$600 each on dry suits - or to be accurate, semi-dry suits - Kokatat
SuperNova suits, breathable fabric, latex wrist seals, neoprene neck seal.
The suits aren't as water-tight as the full drysuit with a latex neck seal,
but they are more comfortable for us and more affordable. They are a quantum
improvement over the wet suits, both in terms of protection and comfort. We
wear ours almost all the time now if we're on salt water (this far north, it
almost never really gets what most folks call 'warm')

Finally, another suggestion - we always carry a dry bag each in the cockpit
which contains everything needed to survive an unexpected night ashore - a
full change of clothes, fire starting materials, 1st aid gear, the makings
and rigging of a crude shelter (8x10sheet Tyvek, folded to fit the bottom of
the bag), and some durable food. In the worse case scenario (flipped, lost
the boats!!!), the bags contain enough survival supplies to get us thru a
couple of days ashore - by then, someone should be looking for us, as we
leave a float plan of some sort either with someone or where it will be
easily found.