First Off - Congrats to @Wimpy and the rest of the Ubuntu-Mate team!!! Great Job in not only getting the release out, but becoming an Official Ubuntu Flavor.
So, I’ve been on the beta for a few weeks, and now that the official release is out - is there anything special I need to do put myself on the official release??? Is it a normal update, or a dist-upgrade, or should I just reinstall the official version?!?
Chris
If you’re already running an Ubuntu MATE 15.04 beta then…
sudo apt-get update
sudo apt-get dist-upgrade
…should be all you need 
After doing doing the this I get a long list of thing to be removed. Is the autoremove command ok to use?
Does the dist-upgrade pull in the features such as totem and the new things in Mate Tweak?
It shouldn’t be a problem!. “dist-upgrade” should pull in any dependencies that the system needs, if totem is a part of that list, then yes!.
Just to be certain, I would use the following command with “-f” on the end (= force dependencies):
sudo apt-get update && sudo apt-get dist-upgrade -f