I'm not sure what your exact question is about echo, but this is how it will work now:
Echo will give you two charges of lava burst. When you get a lava surge proc (or force one using the 4PC bonus), it will add one stack of lava burst without resetting the cooldown. That means that every lava surge proc under echo worth the full 8 second cooldown of lava burst. Without echo, it would have been worth whatever the remaining time is. What Markooo is saying is that, while moving, you will get 2 GCDs of movement with the 4pc, because you will get the earth shock followed by the free lava surge proc (which will not waste any time on your lava burst cooldown if you have echo).