It depends really on what you want to do. The thing to bear in mind though is that python isn't designed to be a web language while php is and because of that it easier to work with php because it does things like db integration, templating, cgi a lot better without any help and there are more web tools that work with php.
Thats not to stay however that you can't build production class sites with python, You can, if you seriously want to use python for whatever reason. I would take look a good luck at zope and plone as these take modpython and build on it to make it more productive for a web application point of view.
Finally yes you can setup urls to sensible names. Though personally I would keep the file extension as it allow you to distinguish what file types are on your web server and the add something like this in the apache config
Code:
<DocumentIndex>
*.py *.php
</DocumentIndex>