Until the Joomla answers proposal is accepted (if ever; I've been waiting a while ...), which is the best place to ask Joomla-related questions? Here or Stackoverflow? Does it depend on whether or not the questions involves programming? Have I just answered my own question? ;-)
Your initial estimate is probably accurate, though there's no harm in asking.
If your question concerns using existing Joomla features or plugins and (beyond configuration) leaving
.php files as they are, Webmasters should be the most appropriate place to ask.
Questions about coding for Joomla or modifying existing code are probably a better fit for StackOverflow, though if you're looking for the theory behind modifications to reduce barriers to search engine indexing, Webmasters may be a good place to inquire and if you are looking for theory behind modifications to improve the user experience I would highly recommend the User Experience SE.