Hello
By sales plan, do you mean that you have PIRs from demand management?
In this case, did you already try transactions MD73 or MD79 to get this information? With MD79 you can even get this information on an excel sheet!
Regarding the past quantities, I don't think that you will have much information, because companies usually gets rid of this information running a cleanup on MD73/MD74/MD75.
BR
Caetano