Drizzle, I don't get books from public libraries so can't help you with that information except to suggest that you check with your library to see if they offer Kindle books. Most do, through the Overdrive service, but some only offer epub. If this is the case with your library, and that's important to you, it may be a compelling reason to choose an epub reader. Here's the Amazon help page about reading public library books on the Paperwhite:
http://www.amazon.com/gp/help/custom...deId=200747550
Project Gutenberg and most other free, legal ebook sites offer Kindle editions as well as epub. None of these sites have DRM-protected ebooks so even if they are only available in epub, you can easily convert them to Kindle with Calibre.
Whether a book has DRM-protection is entirely up to the publisher. Most new releases and bestsellers are protected, particularly those from major publishers, but many are DRM-free. To learn more about DRM and how it affects your ebook purchases, I recommend this article:
[Link deleted. - MODERATOR]
Many users remove DRM from their ebook purchases using Calibre and the tools referred to in the Apprentice Alf article. If you're doing so only for your own personal use and not to promote illegal file sharing and piracy, I have absolutely no concerns about legal or ethical issues, although the subject remains controversial and current US statutory law prohibits doing so. However, the law is still unsettled. There are numerous ongoing legal challenges, as well as pending legislation in Congress, which would permit doing so for personal use, mostly under the doctrine of "fair use" but based on other legal theories and arguments as well. My belief is that some sort of fair use exception for this
purpose will eventually be created either in Congress or by the courts.
When you buy a DRM-protected ebook from Amazon or any other seller, it is coded to work only in the registered device for which you download it. However, you can download additional copies at no additional charge if you have registered multiple devices and apps. Some are restricted as to how many devices you can download to simultaneously. Most restrict to six devices and if you want to download to a seventh, you have to delete a copy from one of the earlier devices. To me, this restriction isn't much of an inconvenience.
You can download and store all of your ebooks on your PC, whether or not they have DRM. If you use Calibre, that's what you'll always do. However, if they have DRM you can still only read them on the registered device you designated at the time of download. If you want to read them on another device, you have to download another copy. If you use Calibre with the Apprentice Alf plug-ins, none of the DRM-restrictions will interfere with your use of purchased ebooks.
Public library books are an entirely different matter. You borrow them for free, for a specified device and a limited period of time, and have no ownership rights whatsoever. Any attempt to circumvent these restrictions would be both illegal and unethical.