Greetings!
As the list's name implies, I'm only a seeker/inquirer, so I may not have the whole scoop here. Anyone else care to jump in?
According to my understanding, the "rock" to which Christ refers is not Peter himself, but Peter's confession, i.e., that He is the Christ and the Son of God. From what I've heard, this is more easily seen in the Greek text; the English structure is a bit awkward.
Insofar as the position of the bishop of Rome is concerned, Orthodoxy is perfectly comfortable with affording the pope the primacy of honor which comes with his position--the first among equals, so to speak--they just wouldn't recognize him as possessing any kind of "special" episcopal powers, as all bishops are seen as comprising a collegiate, organic whole.
This is a quick, hodgepodge answer, but I hope it helps.
-Brett