Those are just Notices, and Drupal 5 does a lot of things with PHP that causes them. Fortunately, Drupal 6 fixes all that. What you should probably do is change the error reporting in php.ini to E_ALL ^ E_NOTICE. Notices aren't dangerous and can be ignored for the most part.

The other problem you're having is some conflict in the character encoding. I'm going to guess that your database has a different collation than Drupal expects. Which is UTF-8, by the way. I don't have any explicit encoding directives in the XML output because I was trying to avoid something like this.