As far as the rear window, do a search on this site for "sliding jaw". You will learn how to take the door panels off to investigate. I just fixed my rear window with the help of people on this site. If you have a drill, it is will cost less than $10 (US)- 5 pds to fix and about 4-6 hours of your time if you have never removed the car door panel before. Better safe than sorry.
As far as the front window, did it always do that or it just started to do that? If happened before, most likely it's due to that accident? If it just happened, then maybe a bolt off the window regulator came loose or came off. Either way, I think you need to take the door panels to investigate.
'89 420 SEL
'90 300 SEL
'68 Olds 88 Convertible
'84 300 SD (sold it)