Joomla 1.0.8 Multilanguage (utf-8) board

Dear Sir or Madam I need professional help for: + implementing a forum/ board on my multi-language site (english german japanese) + make japanese language display properly (utf-8) + important: board language has to change according to user´s choice on the main site (joomfish) + even if user choice is e.g. "english" only "core" of the board should change to "english", posts must be visible in any of the three languages Joomla 1.0.8 Joomfish 1.7 Another issue: upgrading to Joomla 1.5 should be possible/ considered