For the display of the comments on the Invoice and Packing Slip check the settings in the Configuration ... Shipping/Packaging ...
Display Order Comments on Admin Invoice
Do you want to display the Order Comments on the Admin Invoice?
0= OFF
1= First Comment by Customer only
2= All Comments for the Order
Display Order Comments on Admin Packing Slip
Do you want to display the Order Comments on the Admin Packing Slip?
0= OFF
1= First Comment by Customer only
2= All Comments for the Order