Hi Heather,
The Community Events and Facebook Importer add-ons are all separate products, independent of each other and independent of Events Calendar PRO, which is another add-on.
The only thing you need is The Events Calendar, which is free on wordpress.org – then, yes, each add-on is priced individually starting with the Basic Licenses, and you can just add as few or as many add-ons to the free version as you’d like.
To learn more about the benefits of PRO, or any add-on, the best resource is the product page on this site for that add-on.
For example, here are the product pages for each of the add-ons you mentioned today:
• PRO → https://theeventscalendar.com/product/wordpress-events-calendar-pro/
• FB Importer → https://theeventscalendar.com/product/facebook-events/
• Community Events → https://theeventscalendar.com/product/wordpress-community-events/
I hope this helps! Let us know if it does, or if you have any other followups questions/concerns.
Thanks!
George