1: Why not both?

2: That's why there are cards. Also, Diurnal gets more globals than WHM does in the long run.

3: Tap and go. Channel 3 seconds max and you have about the same potency as Asylum and if timed right you mitigate too. Tell the tank to move their behind in the shell and be a man getting as close as you can. Can also combo it with CO and/or TD.

No comments on the other points, Nocturnal is a mere shade of what a SCH can do bar hyper mobility. Only thing I'd argue is to tell your partner to suck up being the off-healer or rotate Clerics/DoTs because Nocturnal is the better fulltime healer (WHM/Diurnal AST have Regen/AB to simulate the fairy heals).
Should there be changes? Maybe, but you're selling it short really badly here.