The full price for Mono will be $69.
Mono is for now limited to a single source and single destination, as the iPad doesn't really pack the punch to do more. Copying a card to two external drives over a single USB bus is a recipe for disaster, so it's best to offload first to the internal SSD.
For that, you'd need to add them to your Camera Roll first, and then make sure the iPad supports the format you are using. Don't bet on a lot of codec support from Apple on iPadOS.
All within Files, and none within Mono. We still don't do vendor lock-ins 😁
Folders too, and even files - like with Hedge.
Yes, although not as deep as Hedge's dupe detection as the iPad doesn't reliably allow for modification date comparisons. Thus, dupes are checked for filename, size, and of course path.