Why be Catholic?

As probably seems evident by now, Michael P.'s recent posts have raised many questions for me.  In his blog letter to me, he said that he does not "interpret the 'apostolic succession' narrative literally."  Later he gives us an insight into his theology:  "I am a post-metaphysical, apophatic Catholic/Christian."   

Before I state this series of questions, I need to attempt to carefully articulate what I am NOT saying or suggesting.  I am not saying or suggesting that Michael P. is not Catholic, is not Christian, is not the right kind of Catholic or Christian, or should not be within our community.  It is not my position to put such labels on others or make such judgments about them.

My questions are sincere and geniune - I truly want to attempt to understand Michael P.'s theological universe. So, here goes.  Michael P.:

What do you mean when you say that you do not interpret apostolic succession literally?

What is the source of Catholic/Christian unity in the absence of apostolic succession?

What do you mean by a post-metaphysical Catholic/Christian?

What do you mean by an apophatic Catholic/Christian?

Is Episcopalian bishop Shelby Spong representative of (maybe a leader of) post-metaphysical apophatic Christianity?

What keeps you in the Catholic Church? Why not join a Christian community (the aforementioned Episcopal Church?), which more closely (I think?) shares your theological universe?

Michael, thank you in advance for your answers.

Pax, Michael S.