As Heiser points out, I do believe that the location is extremely significant to this story.
When Jesus took his disciples to this location, it was a place of worship to the pagan god Pan.
And even more interestingly this location also contained a cave known as the "gates of hades". This cave was the source of a spring that the Greeks believed flowed from hades.
One of the interesting points to this story is that Jesus takes his disciples to the "gates of hades" and tells his disciples that the gates of hades will not prevail against the Church. In Jesus' illustration the Church is on offense, the 'gates of hades' are on defense, and Jesus' expectation is that the Church will overcome the 'gates of hades'.
Jesus' view of the Church on offense has significant implications regarding evangelization and eschatology among other things.
As for "this rock", I do believe that Jesus is deliberately making a play on words involving petros (little rock) and petra (big rock).
To the best of my knowledge this word play only works in Greek (feel free to correct me if I'm wrong), which has its own interesting implications.
I think it's obvious that the word play is directly related to the name that Jesus gave to Simon (John 1:42).
But I'm not going to make any dogmatic statements about the interpretation of Mat 16:18. However, I am inclined to believe that Jesus is referring to Peter as "the rock".