Language localization is on the list, but we don't know if it'll be in version 11 or not. Assuming we can get some help from Interact folks, it may turn out to be a little easier than we originally thought due to some other technologies MC is built atop. One step at a time though.
As for the next alpha, there'll be another build of MC 11 on Thursday or Friday. You'll lose your settings since everything moved in the registry. Some plugins and possibly other things won't work right away. It won't run side-by-side with MC 10 yet.
It'll take a week or so to clean up there and make everything work again.
Then, if things go well, we'll make updated MC 10 and MC 11 builds that can run side-by-side with each other. This isn't earth shattering in and of itself, but it will give us more flexibility in offering future alphas or other products built with Media Center's technology.