[mod_python] Python CMS with PgSQL

I am thinking about developing a CMS with Python and Postgres.  I am developing
on a Linux box with Apache 2.  I have used PHP in the past but my at work we are
considering going with Python as our main devellopment language.  A few
questions for you guys.

1. Is it best to just develop in all Pyhton or to use a mixture of PHP and Python? 
Why orther than personal feelings?

2. What is the best way to template using Python for me to seperate content 
from logic?  All the data that will be displayed in dynamic so I am not sure 
what the best way to template it would be in Python.

Thank you for any thoughts offered.