Ya the 2 packages can do a lot of the same things but do it in very different ways. The java experience will help with python, I would recommend python over Mel for Mayas scripting, since Mel is less powerful and mostly just legacy now. Though Mel is needed if you have to modify existing scripts.
Agreed. I have a few years of Java backing me (haven't touched it for a while), but I'm planning to pick up Python next year. I am really starting to see how Maya would be considered more complicated than 3ds. Both are great programs, but the more I work with Maya the more I'm starting to see the differences.