Here are a few comments about your recent discoveries.
One way to resolve your discovery #1.
Let’s play any song, put it on pause and rewind/forward it a little bit. There is a high chance that player will show that the song is playing, but it isn’t, because we put it on pause before rewinding/forwarding. So the sound is gone.
Fix- force restart
-> Maybe try changing the volume Up or Down by 2 clicks.
Here is a link to a discussion of your discovery #4
Don’t know why, but player freezes when it tries to play this file http://www58.zippyshare.com/v/XGHgn7dx/file.html
-> The Clip Jam will not reliably play m4a files encoded by FFmpeg
http://forums.sandisk.com/t5/SanDisk-Clip-Jam/Clip-Jam-won-t-play-my-aac-m4a-files/td-p/350868
