When exporting .sql via phpMyAdmin do you need to include cache tables?
You can typically skip the data in all of the cache tables.  That is temporary data that Drupal will recreate when as needed.  Basically, the cache tables store data the Drupal creates so that it doesn't need to create it the next time.

You can also usually skip the data in the watchdog table if you don't need the system logs.  Depending on your situation, you may also be able to skip sessions.

There are a few others you can skip (like flood), but they don't usually don't have much data in them in most situations.

Just remember that you want to back up the table structure (ie, the CREATE statements) and just skip the data.

The Backup and Migrate will take care of most of this for you.  drush sql-dump can skip table, data too.

Normally, I just transfer everything when moving between servers.  I just clear cache as part of the restoration process.  I would rather have a bigger file than have the chance of missing something.