Since we are in essence creating a 'new' congregation within PBC (though it originates from within), we are in a way planting a new church - within a church. I don't see any danger in thinking this way - in fact it may be helpful. I am interested in your thoughts on view it this way...
The following is a link to a short list compiled by Tim Keller (who by the way - has massive experience in church plants).
If you want a thought provoking exercise (I hope you do!) - then review this list - while keeping application to what we are doing at PBC in mind!