Hi,
I too, am using a Mac and saw similar problems.
With regards to the order in which the files play, then this behaviour is different, depending on the view you use to choose the music.
Once you've created a database, when you click on the magnifying glass to choose an album/track you have a choice of using the file viewer or the tag viewer.
If you choose the track to play from the tag view, then they will always play back in alphabetical order. I've not found a way to change this, and have actually logged a bug with Pioneer over this behaviour. It effectively makes Tag view totall