Honestly, a drood is must have in raid healing... The hots can make a difference between win and wipe on movement fights, and there's only a few fights when you don't have to move later on. The with some regrowth should keep the tank up and leave time for a bit of raid healing. (also, I like the guy who's our best drood healer, he's fun to raid with XD)
Btw, tip for Nightbane (one of fights I really hate doing without a druid) - on the air phase, when you're all cluttered in one tight group, aoeing - if you have a pally, force him to throw concentration aura on your healers group. Our pally's a tank and he didn't like the idea, but it works really nice, since NB always spits his fire on a healer (usually on me, bah), so uninterrupted cast is the win.
As for not moving the tank... Well, it's not quite possible. The infernals usually land near the ranged group, true, so in theory tank shouldn't move much, but it's not that simple. You need to give yourself as much free space as possible for future infernals, so sometimes tank must move to follow the ranged to a clear place, even if he didn't get an infernal on his face. When you have more practice on Prince, you can assign one ranged to play with his camera turned to see the sky. Takes some time to get used to, but you can predict quite accurately where the infernal will fall, so you can shout "guys, this one goes straight for you" before it lands, so the tank has more time to move. Also, we found saying 'to the door' and 'from the door' more clear then 'right' and 'left'.

That being said, it's all based on luck, though, so it's possible to spend all the fight standing in one place, just pressing your harm spell button of choice. And it's possible that after running around the place all the time, on last 5%, tank gets an infernal showed in his face with nowhere to move. That's why I hate the guy really hard. :/
PS. - what happened to your resto shammy?
Edits are my trademark - I've checked the guild site (awesome, btw, that's some premade thing? Really nice, shows everything important), the resto is enh? Bah :<