[mod_python] migrating to mod_wsgi

We have a high traffic site (thousands HTTP requests per second),  that is
written with mod_python and Cheetah.
We are considering migrating some parts of it to mod_wsgi.

I have a few questions:

1) is there a framework or middleware that we can set up, such that the
existing code that works with mod_python would just work with mod_wsgi?

2) This is about new code, that is yet to be written. 
We only need two simple features from mod_python, namely cookie management,
and parsing CGI variables submitted via web forms (no session management
needed, etc). We also need some very basic templating functionality found in
Cheetah (we could almost get away with string.Template class from pure
Python, but I'd like to have if and for statements as in Cheetah). I would
strongly prefer not to use any large framework like Django for several
reasons (performance, unneeded complexity, security, etc).

What is the best way to proceed: to wrap basic WSGI into our own
light-weight cookie management and variable parsing classes, or is there a
super light-weight and SIMPLE middleware that would do this?
What would you recommend for templating? We do not want to commit to using
anything project that would likely become inactive/unsupported soon.