I have wondered this myself. Should I use Searing Strike a few times quickly or hit them once with that and then use other skills. While I hate all the flying numbers from the TFC (?) mod, I may have to turn those on to see. With large mobs I tend to hit each one with Searing Strike them move around while they sizzle, then hit them with Flame whip thing (I can't keep all these skill names straight...) and that seems to do the trick. When I am tanking, I use Sea of Flames and Searing Strike on each enemy in turn while Blocking. Barely lose any health that way.

I figured different skills would stack, but what about a double hit with one skill. Do you only get the initial damage twice but roughly the same amount of DOT as one hit (keeping in mind the first DOT would do some damage before the second application of the skill). Or, do we also get twice the DOT damage also?

I thought it was stated somewhere before release that same attacks dont stack, so also when playing with other people, if you apply an unstable flame, and another guy places it to, he will overwrite your US, but dont know how it is with morphs, if for example someone took burning embers, will BE overwrite US...?