Hey Neil,
Thanks for reaching out to us. We don’t offer support for customizations here, so the best we can do is point you in the right direction on how to implement what you want, but fortunately that should be fairly simple to do.
I’ll answer your questions in reverse order – to learn how to make an update-agnostic template for any of the plugin’s views, check out our official Themer’s Guide here: https://theeventscalendar.com/knowledgebase/themers-guide/
When it comes to adding links to the iCal and gCal export links, you have two different methods of doing this. First, you could look for the ‘tribe_events_single_event_after_the_content’ action in various public calendar views, and manually add custom HTML for your links after this. Or, you could edit plugin code directly, and find the single_event_links() function, and manually add code here.
I hope this information helps!
Cheers,
George