cache

This has to be done for each site. This is after installing Memcache on your server.

Memcache module

Then, in settings.php, add:

By using field storage, we get access to translation.

We've defined the info files, made them dependent on the core module. That was fun!

Caching is fun to implement, but try to hold off until you have all your functionality in place. As someone somewhere surely said (OK, it was Donald Knuth), "Premature optimization is the root of all evil."

We could define our form messages as a nested array analogous to menu definitions— a form ID,

Fields offer the advantage of understanding translation for user-entered data. Therefore, using fields, there's a potential

On admin/config/development/performance

Minimum cache lifetime
Cached pages will not be re-created until at least this much time has elapsed.
Expiration of cached pages
The maximum time an external cache can use an old version of a page.

What exactly does each mean?

This is quite a major point of confusion for Drupal 6:

http://drupal.org/node/142242#comment-230669

A normal (node) page triggers the Drupal-integrated Boost cache to expire and replace the page whenever you edit it. Editing a view unfortunately does not have such triggers. In this case the views are attached to a node, so simply resaving the node rebuilds the cache.

In most cases the view itself will not be modified, rather, you will add or edit a node associated with a view which also refreshes the cache for that views pages. (Note this takes a bit of processing to look up, and i don't think it will apply for blocks.)