For that matter, regarding AC at level 30:Predator's Hide +6 = 45 against your quary, 42 against everyone else. (+3 to all your other defenses as well against your target).Agile Nagascale +5 = 46 AC when you aren't bloodied, 43 when you are (+1 to fort).Dwarven Elderscale +6 = 46 AC all the time.Agile Elderscale +6 = 49 AC when you aren't bloodied, 46 when you are.
Given that Extra Damage Action only affects Standard Action attacks, I don't think there is any difference between spending the Action Point immediately after Trip Up or after Off-Hand Diversion
I would still say not. You won't be in Melee Range all the time, and +1 to hit on what is otherwise a very lackluster Ranged Basic Attack is greatly appreciated.
No offense intended, LDB (I love your ideas), but your level 12 nova is a bit disengenuous: you are sitting still for the first round and not moving until the last action of your second round, spending all of your moves for minor action to self-buff and (2nd round) attack -- yet you are counting all of your prime shot damage bonuses, assuming that you somehow magically have setup prime shot conditions on your target w/o you actually moving to your quarry. That maybe a lot of theoretical damage, but its not very functional.
I find Immediate actions to be very useful to pump damage in real game scenarios: you get the same damage output by subbing Distruptive Strike for your 3rd level minor action attack power, but save yourself an action (and frequently some damage). Ditto for Battle Awareness when the back-line target that you've picked to solo tries to shift away: extra damage w/o spending one of your valuable actions on your turn.