Question: how to manage the informations saved during a session?

Hi,

When I do large computations in a worksheet and that I manually save it, I get a message in a pop-up window which asks me if I want to save these calculations too:

1. What is it that is really saved if I answer "YES" 
2. As I always answer "NO" how can I force MAPLE to ApplyGlobally this answer (I wasn't capable to fin it out in the Preferences>Interface menu).
3. is this preference accounted for during AutoSaving?

Always in the goal to save only the necessary informations (in a mw format, export to mpl format could of course be a solution), how can I remove all the outpouts (and more specifically all the plots) in the current worksheet?
Presently I'm doing this and, before my last  saving, I turn TF to false and rexecute all _display commands ... not very practical, I agree

restart

_display := proc(tf, graph)
if tf then print(graph) end if:
end proc;

TF := true: # or false if no plot is required

# for each plot:
p := display( something ):
_display(TF, p)

Thanks in advance