Forizzle: if you want to see a lot of this advanced shit in action, I reccomend you check out some DBR videos.
http://video.google.com/videoplay?docid=410178209619848304&q=dbr&hl=en <-- that's their longest one, but they have a bunch of individual charcter videos as well. Just do a google video search for DBR.
EDIT:
Wave-dashing is when you jump and immediately airdodge diagonally into the ground. Your momentum from the dodge is transferred into a foward or backward slide along the ground where you can do any move, like a down-smash or a foward-smash.
So it's a roll dodge.
No, it's not. It's faster, more controllable, and more versatile, because you can do any attack out of it, before you even finish moving.