Matrix fields within matrix field Is there a way to place matrix fields inside of matrix fields or also to setup a matrix field with existing fields? 

We are currently trying not to have duplicate content in terms of fields, but that doesnt seem possible?
Matrix within Matrix isn't possible... yet. Brandon has stated a few times that it's part of the long-term plan, and it's really more of the UI which is a stumbling block, rather than any major technical challenge.


  ... Matrix within Matrix is still something we intend to get working at some point.
  
  … Matrix within Matrix will be coming eventually. The UI is tough, but the code is all in place.


In the meantime, you may want to try using the LJ Dynamic Fields plugin. It may not be exactly what you're dreaming of, but it can certainly help keep things a little DRY-er.