DRM is an issue with *all* readers.
For now and the near term, alas.
*How* it is an issue depends on the reader.
Not all ebooks use DRM but most all library-loan ebooks use it.
Given your interest in library ebooks, it is an issue you can't avoid since DRM is what enables Libraries to lend out ebooks; no DRM, no lending.
As your library pointed out, there are two flavors of ebook DRM that support timed ebook reading (=Lending) by providing ebook reading rights that expire after a given date.
Overdrive is a company in suburban Cleveland that provides public libraries with the back-end "plumbing" and services they need to offer ebooks and they support both Mobipocket DRM and Adobe Adept DRM.
Ebook readers generally support one or the other so the choice of an ebook reader device determines which library books (if any) you can check out. (It also determines which online book store(s) you can buy ebooks from.)
In this context, Sony epub = Adobe Adept epub, as it was the first ereader to support Adobe's DRM scheme and is the most common, so far. There are dozens of other products that also support this baseline Adobe DRM and the Aztak line is among them.
So if you see Sony or Adobe epub, the file format and the DRM will be the same and you would handle moving the files roughly the same way.
As for charging, just remember that these days a *lot* of devices (cellphones and media players chief among them) use USB for charging and a lot of devices come with USB ports (game consoles, DVD players, even TVs) besides PCs. Odds are your relatives will have something you can use. Anything that will charge an iPod or a Blackberry (for example) will charge the reader. Failing that, USB power adapters run around $10 for most countries' power systems and should be locally available.
And that's assuming your daughter gets to drain the battery to start with: 2 weeks between charges is a somewhat conservative estimate based on heavy usage; the actual spec is for around 7000 pages worth. (Hopefully she'll find other things to interest her for at least part of the day.
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