Arc-problems transferring books
The Kobo desktop issue is not an issue. It's doing exactly what it is designed to do. When my daughter plugs her Kobo Touch into my computer when she wants to purchase a book, it shows her purchases/library, her recommendations, her wishlist, etc. She even gets to use her own credit card to pay for purchases.
As for Calibre, you are going to have to wait for the driver Calibre uses to talk to the hardware to be created. Last time I played with a friend's Kobo Vox, I had to attach it in USB disk mode for Calibre to recognize it.
For ADE, it is not on the Adobe supported devices list so you are out of luck until it is. Oddly, the Kobo desktop app for Windows does show as a support device. The friend with the Vox was using an application called Overdrive Media Console to allow him to directly download library books to his Vox without going through his computer and ADE. I'm not sure if this application would work on the Arc though it was a more or less standard Android app so it should work.