Dread Guard: Phase 1 looks pretty easy. Phase 2 is pure chaos with lots of single-target spike damage on random raid members. Phase 3 is slightly less chaos, but only slightly. Open question: how you work phases 2 and 3 for force conservation, single target heals, and AoE heals?
On phase 2, try to have your group position itself and move so that aoe heal use can be maximized. This means as little motion as possible. An aoe heal is still quite effective if you place it on the edge of where the group is currently with some of it advancing into where the group will move next. When someone in melee range drops a green circle, the tank can move the boss slightly enough to get everyone in melee range out of the way of the circle while still staying in the aoe. Watching for spikes from force choke is important, but you don't need to necessarily worry about them dying from another hit right after the choke, so you have time to get them up. Also be aware of when the other healer has doom, as they will pretty much only be able to cast instant things while they run through the circles. For an op healer this is less of a gimp, but being limited to resurgence and static barrier can reduce healing significantly for the duration of doom. Last thing is try to use aoe heals to recover health lost to consumption as much as possible. I'm currently working on this myself, and avoiding cases where I happen to be standing in my own aoe at full health. I will purposely use consumption say two times before casting an aoe so that I am healed back to full (assuming I'm not taking a lot of other damage). Personally, this was the hardest fight for me.
Kephess: The only time salvation seems useful is when Kephess starts his laser blast and is about to be knocked down, and only if laid down immediately. But that means I'm not focus healing the person taking laser blasts for 1.8 seconds...and they take a LOT of damage. Do you go with salvation here, or bubble and start pre-casting deliverance? What about nanites...is salvation good to lay at the tower that people are going to be clicking on?
Aoe's work for cases near the pillar, but damage going out is not as high as the Dread Guard fight so it's easier to use your single target stuff. For the person taking the laser beam, static barrier and best single target heals work best, but you could add an aoe if other group members in the area are low as well. You will want to do the same thing for people getting jumped on in the second phase. And of course, aoe in the burn phase helps a lot.
Terror From Beyond: Phase 1 seems like pretty standard stuff, no real worries here. Phase 2 I'm not sure about. In story mode, I alternately placed salvation on the DPS platform, which was kinda pointless since they weren't taking any damage, but would be a good thing if they accidentally take a slam or something. I also put it on one of the tank platforms as an extra HoT, which did make healing that tank a lot easier. And I tried it on my own platform for force management. None of which felt like a particularly optimal thing to have done at that point...nor was I happy about the amount of healing I consumed from the other healer as a result of noble sacrifice. I don't think we can have that happening in hard mode. So again, open question, what do you do here?
I wouldn't use an aoe at any point during the second phase. I believe that aoe heal only reaches efficiency greater than your other heals when it affects three or more targets, and at no point during the fight will three people be on the same platform (except for dps, but they aren't taking damage). So, just stick to your single target heals. The one thing to watch out for is the aggro generated at the beginning of the second phase. Make sure your tanks are taunting and using the highest threat output they can as large heals in the beginning (which might be necessary) can pull the boss due to the 75% damage reduction. And having the boss on you for more than five seconds is basically death.