On General, if you get "shadow crashed", can you teleport while you're flying backwards?

that is possible, yes. Same goes for algalon, if you get hit byt the meteor crash and fly up in the air, you can teleport down to avoid falldamage.

A few things that worked well last night on our Northrend Beasts HM kill:

1. Before Acidmaw/Dreadscale engaged, I dropped my teleport near the Dreadscale tank in case I got paralytic poison.
2. With no run speed buff during Icehowl, I suggested dropping a teleport near the outside of the arena and staying (relatively) close to that for one of the other warlocks with higher latency. The hotfix already implemented seems generous enough but this could still help.

You can place a circle in the mid of the room @ Anub'Arak P2 and manage a kite back and forth across the room without requiring a Hand of Protection (if you cannot stack >3 paladins), as long as you get a Body & Soul shield after you teleport.

It's also handy if you manage to get alot of scarabs chasing you, to not get too many debuffs.