If you're going to go with a shammy as primary healer (which you totally can, by the way) and want to keep the entire group F2P (which will be hard, but not impossible), then I would go with a shadowknight instead of a warrior. The reason is the SK will get spells/taps to help keep themselves healed, but the warrior will not. The warrior and SK both are extremely gear dependent, but the SK's ability to tap to help keep themselves alive might offset some of that gear dependence (for your purposes).
Regarding the three rogues... remember that rogues are the only class that I know of that have an alliance disc that can be triggered by other melee classes using poison proc potions. So, one rogue using alliance can have their ability fulminated by zerkers, rangers, monks, beastlords, etc. You don't 100% need to have three rogues. Honestly, rogues are great dps, but I would probably swap one rogue for a zerker and consider swapping another rogue for a beastlord or ranger (for adps purposes). Rangers melee in ToV outside of when they're using their big bow disc (pureshot), so they can get up to good numbers if you have a decent .ini.
Forget all of the above about the rogues if all you want them for is dropping campfires. If that is the case, just get them high enough to get the max SoS AA's and then roll other toons on the same accounts to create the group you actually want to run 100% of the time.
Just my very cheap 2 coppers