Earlier quoted context omitted.
I think in most cases when you add a feature you end up touching everything in each of the layers. It's only when you want to change something that it's possible that you might just be restricted to one layer. I think the idea of the template is that you have one template and many views, and possibly that a template can be created of many different smaller templates, e.g. header, footer, sidebar. Here is an example o…
Yep, all wrong :) You want a custom filter: http://www.djangoproject.com/documentation/templates_python/
Other types of complexity can be handled in custom template tags too.
The easy way to look at them is you could write your own 'filter' or 'count' or any of the tags you see.
However, most of your needs can be met by the built in filters.