I'm impressed with your dedication 6 five man teams at/above 85 during one RAF period is astonishing.

Professions:

Definitely make your tanks be the tailors (and possibly the enchanters as well). Tailors get extra cloth drops only they can see. As for what professions you want extras of, it is probably too soon to tell. Historically you can stack transmute alchemists.

This xpac there was a gating mechanism on almost everything good, making stacking scribes (http://stormspire.net/professions/13...s-1-580-a.html) really good and if you follow that guide I just linked, super cheap to level additional scribes(under 2k) after you have one at 600 that can trade the ink of dreams. Tailors have daily cooldowns, which is nice for making bags but obnoxious this xpac because there is a location requirement for the daily cooldown and lets face it no one is dragging their ass out to the stupid silken fields every day. In terms of gear making you really only need one of each gear-maker, you'd probably never make back the cost of levelling up additional LW or Blacksmiths because the period where their cooldown gear was really valuable was so short.

I wouldn't worry about having a gatherer in each of the groups, except mayyybe skinning, because even out in the world you just aren't going to gather that much unless you are specifically doing a gathering run on a specific toon. In dungeons you'll gather almost nothing.

Raiding/challenges:

In your place I would probably just make a spreadsheet with all of the bosses in each of the raids from WOTLK (25 man difficulty) and Cata (10 man difficulty) and do them in order. I'd also probably try to xp lock an 85 team and see how far I could get at the 85 heroics.

SOO is a great raid. I'd farm that 496 gear and then take a couple of toons through all of the LFR raids just to see the content.