Hi, Don!

Specifically in answer to your question 2 (f): Habitability: I have served aboard Daphne submarines, and they are very comfortable. Of course, you must take into consideration that it is a vessel built more for war than anything else, but the French designers did a very good job.
The boat is airconditioned, mainly to extract moisture from the air which would otherwise damage electronic equipment, of which there is a great deal. As a result living conditions are cool, the air is fresh all the time, and oxygen can be replenished and carbon dioxide removed at any time. Food is good, too. The best thing, though, as anyone who has been on these vessels, are the bunks! I don't know exactly what the manufacturer did, but those matresses are the best in the world!

Hope that helps

Garth