Answer:
Not all the secrets behind all his tricks are known, but one thing is known: they are indeed tricks.
For example, his levitating trick, where he levitates from the sidewalk up to a high curb, is achieved putting a locking false leg down one of his pant legs and cutting a slit down that pant leg so he can step out of his pant leg and on to the curb while keeping his real leg hidden by the false one.
Search YouTube for "Criss Angel Revealed" and you'll get a lot of explanations on how he did many of his tricks. :-)