1 adding a track to an existing playlist - no problem on my XP SP2 laptop.

2 checkout to default playlist name on SD (eg playlist1), then rename playlist to something else - as above again no problem, new name shows up in the 7k fine.

3 is simple, the mute time setting is in the general setting for jukebox, and thus applies to jukebox playback on the pc and thus nothing to do with sd playback in the 7k.