Except from Amazon, e-books can be downloaded from all shops, via USB or via Tolino Cloud. Adobe ID is required, the "Adobe® Digital Editions Software" mentioned at Exlibris does not need to be installed. S.a. tilino-Hadbuch chapter 10.
Yes, I had a file of a book I bought from Exlibris on my PC and I could easily drag it over to the e-reader and read it. It also has a web browser, which I can use to log on to Exlibris.