As features are added, they are then explained in the Kobo blog.
This link is to the latest update.
The Kobo Touch will override the books formatting if the book is an ePUB (without DRM or with ADE) or kepub--but not if the formatting has been changed by using and applying the Calibre stylesheet. I use Calibre for library management, but I do not do anything stylistically with it. They do somehow
lose their DRM along the way. All of the Touch features available for the format (ePUB in my case) work on my books sideloaded from Calibre without any problems.
Tim Legge has made a change fairly recently that lets people change covers without having to invoke the Calibre stylesheet.