As to the whole moving to Kobo thing, they have (in my opinion) one of the best sets of eReader devices right now. Their files are basically epub, the DRM is pretty easy to strip even without a physical eReader, just using the desktop app.
Their eReaders handle side loaded content fantastically; most just throw series in a big pile without respecting series order or even that some are in a series together, but with Calibre you can easily set what order they are in and have a spot where you filter by series on the device. I’m happy to answer questions or we have a community at !kobo@lemmy.world too.