No time just now, but you're going to need to discuss different types of expression. Simple point, but one which lots of analyses ignore. e.g. improvisation can suggest 'I'm happy'/'I'm hyperactive'/'I'm angry'. It cannot suggest 'I have black hair'/'Shaken not stirred' etc. Nor can it confirm anything, as saying 'I am happy'/'I have black hair' almost certainly does. A lot of this gets obscured by the romanticised blustre surrounding lots of jazz - 'when he played, you could see the colour of her eyes' etc.
Sorry - a garbled paragraph, but a start!