highlight utility skills (cleanse, interrupt, ...) when effective

[INymphI]

Stunnable/interruptable stuff share the same indicator if you look at the cast bar, if I'm correct.

sadly no, not on bosses at least, maybe on trash mobs. that dungeon boss hermes has a cast which gives himself a dmgup buff. it is interruptable, but you cannot stun him/it.

KB is pretty obvious outside of savage(?), the markers on the ground fanning outward in a circular direction/out in one direction/colored vomit puddle in the middle of the arena/insert random pattern here.

yes and no :-) i know arrows and that blue "knockbackpuddle" are a nice indicator, but in the newest alliance raid 2nd boss one can not use knockback immunity...and there is no particular indicator, we just have to try it out. same in savage, sometimes it works, sometimes it does not.