re: availability, try emailing the author of that book series as it is likely a mistake on the publisher's side. I was reading a trilogy on the Kindle, only to find the last book unavailable in my region; I emailed the author asking why that is, and got a reply the next day saying it was a mistake, and the final book became available two days later.

As for DRM, I just use Calibre to strip the DRM off my Kindle purchases. Annoying that I would have to do that, but its better than not having the option at all.

As for value-added from Amazon, I love the free international 3G access for the browser. It is amazing if you travel a lot and the money saved from data roaming fees has already paid for the Kindle itself.