Regarding your second point: I'm not exactly sure about the details, but you could assign a drive letter to your music collection on your Terastation, and when

Regarding your second point: I'm not exactly sure about the details, but you could assign a drive letter to your music collection on your Terastation, and when you're traveling, you could reassign the drive letter to your music folder on your external HDD. This is not perfect, but could be a possible workaround.