Thread:Support/internationalization of interface messages in translate extension/reply (3)

For 1) see https://bugzilla.wikimedia.org/show_bug.cgi?id=2085 (the answer is: not by default). For the other parts, I think the answer is also no.

I assume you have already read https://www.mediawiki.org/wiki/Special:MyLanguage/Help:Extension:Translate/Unstructured_element_translation and https://www.mediawiki.org/wiki/Help:Extension:Translate/Page_translation_administration which provide some hints how to handle content translation with what is currently available.