Hi
Should I set these from within joomla, or is this ability no longer important for seo?
When I started sh404SEF, at the end of 2006, keywords were already not used by Google, although some other search engines of the time would use them.
Since the early 2010, Google just don't read them at all. I'm not up to date on Baidu and Yandex, which were the ones using them for the longest time, so they may still use them somehow but that's unlikely.
The only reason to spend time on entering keywords is if you have an extension that uses them. For instance, I know there are a few extensions that use them to match "related pages". But for SEO purpose, no, don't waste time on keywords.
Note that you can still enter meta keywords in sh404SEF, you can click on any URL in the SEF URL manager and the "Title and meta tags" tab has a "Keywords" field. Just don't waste time on that!
Best regards
Yannick Gaultier
weeblr.com / @weeblr