The Kobo Utilities Plugin has poor formatting but it's MUCH faster and gives more information. The Annotation Plug in is more limited and VERY slow, maybe if you have a lot of books.
You need Calibre and the Kobo Utilities.
Also Calibre converts Docx from Word or LibreOffice Writer well to ePub.
Also best way to read web info for your research is via paste in to Wordprocessing, clean up and save as Docx, then import to Calibre.
You can also convert DRM free Amazon books. Buying Amazon eBooks is best done via PC for a kindle eReader.
Smashwords sells ePub and no DRM
www.gutenberg.org is good for public domain/out of copyright, but I find their Kindle mobi format works better and I convert to ePub.
It's always best on ALL eReaders to load ALL eBooks via USB, so called "side loading", then you have a backup and privacy.