Ivo,
It sounds like it may be worth spending a little time learning Google App Engine first, before attempting to deploy / host a site as complex as the Khan Academy. I know from my own experience that taking some time to become familiar with the GAE (which the site is built upon) paid dividends when I wanted to start playing things :-). It will definitely help you to figure out how Python, Django, GAE and Khan source code interact.
There are some great videos to get you started - take a look in the google developers youtube channel:
Hope this helps a little!
Nath