Someone on a Kindleboards.com thread posted a link to the Amazon.de Author Central account. That made me realize (duh! doh!) that my frustration with being unable to customize for DE (my husband and MIL are fluent German speakers and are offering to translate my description/bio/etc.) is not a function of Amazon, but of my own ignorance!
For anyone else who didn't know this, here are links:
If you don't speak or read German (I read enough to find a bathroom, order a beer, or upload a bio and picture), I suggest you have one of the other two versions open in a separate tab, and then toggle between the two pages to make your way through the German site. The interface for the UK version is similar to the DE one (the US version has more features), so that's your best bet for being able to understand the DE version.
I've now updated all three with my bio, Twitter feed, picture, etc. I can't wait to get my German description and bio up -- maybe I'll make a sale, finally, there LOL.
FYI -- hope this helps someone else!