Hi JM and thanks for getting in touch!
Great questions.
The Advanced Widgets are a set of widgets you can embed in any page or post. There are several widgets in total, including:
As far Additional Fields go, they allow you to create custom details about an event. For example, let’s say your event has a theme. You can add a custom field for Theme and have that information display in the event details. More on this can be found here.
The Events Calendar does not include social sharing by default, but we have a handy tutorial on how to set that up with other plugins.
And, absolutely, you can add images or any other content you would like to an event when filling out the Description field just like a default WordPress post. 🙂
Does this help answer your questions? Please let me know.
Cheers!
Geoff