Just as a tip - everything on Remarkable is PDF. Yes, it reads epub files but it then converts them to a PDF for viewing. On RM1 this could be a bit annoying if you are the type to change the font style or size as it then must recreate the pdf - that can take more than a few seconds on a large file.

I've taken to using calibre or similar programs to output the epub as a pdf (with my preferred sytle at RM screen dimensions). I've also bulk cropped pdf's to the RM screen size instead of using the built in crop feature.