Hi Joe,
Welcome to the forums! I see you have a few other threads open and we’ll do our best to get to those as quickly as possible. 🙂
Great questions. Yes, it is possible to create your own custom fields in Events Calendar PRO, which can then be added to Filter Bar, which I see you already have purchased. That would allow guests to filter your calendar by county, should you use County as a custom field.
And, yes, you can also use Event Categories to categorize events by the name of a specific county. The calendar does include an RSS feed that gusts can subscribe to for a specific category. That URL, for example, would follow this format:
[your-site]/events/category/[category-slug]/feed
Does this help answer your question? Please let me know. 🙂
Cheers!
Geoff