@Shiva: You don't download Calibre to anything but your laptop. You simply copy the file you want to your device. There's a way to sync to your device, but I don't have my micro USB cable with me to write up the exact instructions for you. Basically, once you have Calibre installed on your laptop, you populate your digital library (books, articles, etc). Then, if you need to, you can convert your library media to a format compatible with your device (I prefer PDF because I'm anti-proprietary *grin*). Then you sync the media to your device. Or, if you prefer, you can just navigate to the file that has your book/article/whatever and copy the file over.
There are ways around DRM (it's my book dammit), but the legal community frowns on them. Take that as you will.
@snowbot: With you on changing out book covers. I've been known to go with a worse-quality image just so it matches the cover the book had when I read it physically (have a library of my old sci-fi/fantasy books so that maybe I can one day convince myself to purge my physical library).
@notmensa: I'm working on my PhD too. Funny how easy it is to get distracted by everything BUT your dissertation. Like, oh, checking these forums *BIG GRIN*