Most of the steps you only have to do once. It's not as bad as it seems. After you find your book at whatever system your library uses, you checkout, then download it to open in ADE. Then drag your book to your reader which will be connected to your computer via usb.
I suggest contacting the library and asking what they use for ebooks (My local library doesn't offer overdrive so I had to get a card at the next city over), then see what kind of formats they offer (epub, pdf, mobi, etc...) to make sure you get the right device. What if you buy a Kindle and find out your library system doesn't have mobi files? I also heard (but I'm not sure on this) that to put library books on a Kindle you have to run a script first.