Hey Christian!
I'll try my best to answer your questions:
1, 2) The user sets locale at /acs-lang. You could of course add this setting to your master template (to appear on every page) or on the start page.
3) Yes we have many people working on translations. Especially the german translation will be done by professional translators for the Heidelberg University. Carl Blesius is in charge of that.
4) I think some people are, but I'm not sure. Note that all applications in dotLRN have been internationalized.
5) If you mean selecting different templates (different layouts etc.) for different languages we don't yet support that feature. It's something we considered but never got around to. It could be implemented fairly easily though I think.
Hope this helps!
/Peter
