[mod_python] advice for a multilingual app

Hello,

I'm going to create a web site that will have the same content in
several languages and some additional services for registered users.
User preferences (like the UI language) should be preserved within a
session, also with cookies disabled. Additional services may require
cookies.

Long-term goals are:

* Minimalism. Anything not explicitly enabled is disabled. A framework,
  if any, is preferably a set of libraries rather than a run-time with
  hooks.

* Developer efficiency and maintainability through the optimal program
  and data organization, concise expressions and avoidance of
  unnecessary manual work (like updating the same code in five pages, or
  not using available free frameworks). E.g., pages in different
  languages could be organized like sources using gettext: single master
  page with the text in the primary language inline (and not as a macro
  defined in the language-specific file), pages in other languages are
  generated using other files.

* Performance through caching and minimum dynamism. E.g., pages in
  different languages could be generated once (either via make before
  deployment, or on the first page access).

I'm going to use mod_python with the PSP handler. All texts and links
seem to have to be generated. I'm going to develop new code for that.
mod_python seems to handle sessions using cookies.

Now, the question. The last time I developed web apps was 2000, at that
time I was using PHP for a small intranet. I don't know whether the
above concerns are of any importance for a busy web site. So I would be
happy if you could share your experience regarding what to pay attention
at. A secure Python programming guide and framework recommendations
would be welcome. E.g., I couldn't find any standalone input sanitizing
functions for SQL or HTML. I've looked at WebFrameworks on the wiki and
read a little about AHTS, Albatross, and markup. However, they don't
seem to do exactly what I want.

Thanks in advance,
Baurzhan.