On the positioning of Cho'gall on the throne, watch out as there are a couple of fire patches to watch out for.
As for you poor healers you are best with your most mobile healer going with the add tank, plus if its a sexy tauren they have war stomp to help with worship on nearby players which is an added bonus. This means if Wyrmy is tank healing in melee all he has to watch for is shadow crash and fire patches plus he has arcane torrent to help if worship missed. His aoe heals will be more of use here as well.
As for mana well its a case of sensible healing and no missed worship's (as this causes cho tank to take insane damage wasting extra mana for later). First few times i tried was ok at start but then come final phase was running on empty. So any mana regen jiggery pokery tricks your healers have should be used as much as possible eg Innervates,mana tide and any fail preist doings. So what i decided to do was get the core of ripeness trinket i will pop that then innervate just so i have them off cd by the time the transition phase begins.
Healing the final phase is fun but a pain, especially if your precious blue bar is almost gone. But its still possible to get through it on certain classes with 10% mana (Druids Rock
) The beginning of the phase (as long as corruption levels nice and low) is easy as not much damage, but by they time the 2nd lot of tentacles appear you will notice people dropping. Then if a 3rd lot raise their ugly little heads its omg blow everything time as things can get a little hairy, aoe heals,potions of save my ass the lot and hopefully that should be the end of the two headed fool.
One other thing use the spirit flask for this fight as any combat mp5 is win.
Anyhoo hope this helps and have fun