Hey Dan,
All good questions, but my guess is that it is way too early to get the answers you are looking for, since the BigA has only been for sale in the U.S. for about a month now. But based on my limited test of the Adventure, I would say that it would be an excellent boat for what you have in mind. It tracks well, is very stable, is the fastest Hobie yak out there at 16 feet, has the Mirage pedal drive, plus you can sail it. Add an outrigger or two, and you should have a great boat for interisland travel--even the Molokai Channel perhaps! Also Hobie is working on a new, larger sail for the BigA, and new, more powerful Mirage drive flippers.
If you think you might be in need of some extra flotation, a simple solution is to pack the hull with a bunch of plastic pool noodles. So far as lights go, I mount a waterproof, personal C-light on the end of a PVC pipe about 4 feet long (so it can be seen above your head while seated) and then put the PVC pipe in a rod-holder. However, for max visibility, the PVC pipe needs to be vertical and not canted off at an angle as would be the case in most built-in rodholders. However, boat lights are up to each State, as I recall, so you need to check your local State regs on this. Here is a pic of the BigA under sail with the standard Hobie sail kit.
