Drupal 6\'s cache can be set to disabled, normal or aggressive. I cannot find these options for my Drupal 7 installation. There is only a button that flushes all the cache but i
There are many different levels of caching involved.
The menu system is not actually a cache. If you change anything in hook_menu(), you need to rebuild it. devel.module provides a handy link for that in the development block.
Additionally, Drupal also caches hook implementation and many other things, which you can clear with another link in the development block or if you have drush installed, with "drush cc all". There is also a way to disable it completely but that could make your site quite slow: http://drupal.org/node/797346