I haven't researched this too closely, but I'd have to guess a "no" on all of the above. Even the PSR-E463 cannot control the volume and balance of the style tracks, though it can mute/turn off individual tracks (or at least groups of tracks, as there 6 buttons for switching style parts on and off, so if there are 8 MIDI channels for the styles, then some channels must be doubled up on the buttons). But as I look at the front panel of the E373, I do not see the track on/off buttons that are on the later E400 series keyboards.