Hi Barry,
The Events Calendar (free version) has category views built in to it.
So if you have a category called Convention the url to see the Calendar Views would be”
yoursite.com/events/category/convention/
There is a feed setup for that view as well:
yoursite.com/events/category/convention/feed/
We do not have any other way to feed content out of the site.
The filter bar add on can sort the main event views by categories, but does not have a feature to prompt a visitor to select a category before showing events.
Let me know if you have any follow up questions.
Thanks