For the slight rollback - it's normal, use the parking brake.
My guess at your shifting noise would be transmission mounts. The clunking only happens at highway speeds? During downshifts or upshifts?
'04 ML500 - 53k, Inspiration Edition, Desert Silver
'11 Audi A4 Avant - Brilliant Black
'87 300SDL sold
'99 C280 Sport sold
'85 190E 2.3 sold