Vlad
What about saved passwords?
AFAIK Firefox doesn't allow clearing passwords on exit.
So basically if I would leave the settings on the image, browser would delete all data.
Yes, the browser will clear selected options on exit.
Site settings
refer to site specific preferences (that have been modified from default).
It seems like it would be useful to have these same settings for
I don't know the positives for having all these settings for when a tab is closed (maybe, private window can be used for this or CookieAutoDelete extension)
I think, it makes most sense for when browser quits.