I registered at the site (http://www.caterpi.com/people/545002) and want to help with the translation of the site, but it's not possible to choose a language there besides what's already offered. Where should I ask to start translations into other languages? (Like Dutch, Esperanto and Portuguese).

One essential point... You don't see anything about the native language of the translators (and nothing about e.g. Brazilian Portuguese and European Portuguese). Also local languages are not there but might be in want. (If you put Esperanto in the list, better also Frysian for example)

But please try to find a way to not get details in the way. It's a nice and clean site and that's good :).