Hi, Squatch-
I'm relatively new to the forums , and happened upon this topic and decided to weigh in. Sounds like you've got a lot of questions and factors to consider- not sure if I can help, but will offer some perspectives.
Consider your shelf or display space, budget, time, and amounts of detail to incorporate into your build,when deciding on your subject.
Remember too that when building your subject, it's important to consider whether you're modeling your carrier at a particular time and place (e.g. Enterprise at Midway, Santa Cruz offensive, or in her final wartime fit before being taken out of the fight in May of 1945 by a kamikaze off Okinawa) or as a more generic reperesentaion of the class.
I've built three Yorktown-class carriers (Tamiya 1/700 scale Enterprise, Revell's 1/542 (?) "Battle of Midway" carrier 3-in-1 model, and the more recent Revell Yorktown repop.) If you decide to go that route, the Revell kit has a very accurate hull for the Big E, but needs minor mods in bow shape for the Hornet. Tamiya's mold is a waterline hull, and portrays her in a late pre-war/early war appearance. Fit overall is good, but detail is lacking as pointed out elsewhere in the thread.
I think one of the reasons a CV6 kit has been shied away from by manufacturers is that her refit history is far more extensive than that of her sisters. Drastic changes in armament fits, catwalk structures, radars and comms antennas, searchlight platforms, aircraft, addition of anti-torpedo blisters, and even the camouflage schemes she wore during her service make her a challenge to even the most experienced modelers to build.
And incidentally, that's a important consideration regardless of which WWII carrier class to build. Given the staggering pace at which innovations were introduced into US naval aviation, both in field modifications and Stateside refits, do your research carefully. If and when you need to purchase aftermarket kits for your subject, make sure it contains the parts, aircraft or structures needed for the time period you wish to portray in your finished model.
My Revell Yorktown repop was built as a prewar version, with relatively minor mods to the island, a painted wood deck with simulated two-color planking, and deck striping and decals, but without the big "Y"painted on the island structure. Added rigging, "*** box loudspeakers to her signals bridge, and deleted the "theater marquee"structure located aft on her portside island. planes were painted in prewar silver and yellow with painted engine cowlings, tail planes and wing stripes. Probably not accurate to a T, but a very good looking final result.
Good luck and good hunting to you in your decision, and do keep us posted