I feel like this is once again overhyping how useful Symbiosis is.
1. If you can spare a healer to pop traps then perhaps you should replace that healer with DPS. There's a reason most healing priests don't pop traps with levitate but leave it to DPS.
2. Those are nice, agreed, but not as awesome as Void Shift or Ascendance, wouldn't you say?
3. I'm not sure if that would work, but theoretically it sounds nice
4. You're really exaggerating claiming it's god-like. It's very handy in some situations, yes, but those situations are hard to predict. I've certainly never had to help our tanks kite on my priest, I think they'd get quite pissed off if I pulled anyone without them asking me. :P
5. Yes, Spiritwalker's Grace is amazing and awesome and bordering on OP. :P
6. Why do you need 2 Cleanses in the raid? The paladin can already do it, you are merely replicating an existing thing that the raid group already has.
7. Yes, the additional tank CD is nice.
8. This can be useful occasionally, yes. But again, is it as awesome as Ascendance? :P