The door weather stripping is glued in place. To put in new you would take note of exactly how the original was put in and put the new in the same way. I need to do the same in several of my cars and the problem I have is finding the right weather stripping the same as the original.
My 1987 Chevy Celebrity with 2.8 V6 was doing the same thing. I cured the problem by replacing three dead fuel injectors.
The dog bone is not repairable, simply replace it.
To give you an answer we need to know more specifically what the problem you are trying to repair is.
Replacing a head gasket is a rather lengthy process, much too long to try to detail in this space. I would suggest that you consult a factory service manual, Chilton or Haynes manual.
OK, you have a 1982 Chevy Celebrity. Do you have a question?
You have a small "EVAP" leak. Start with replacing the fuel cap.
Yes there are Torx fasteners used in a Chevy Celebrity.
There is no such thing as a 1991 Chevy Celebrity
There is no relay for the tail lights on a Chevy Celebrity.
Chevy didn't make a 1981 Celebrity
Replacing a wiper motor on a 2004 Chevy Impala can be difficult. It is best to take it to an auto repair mechanic or an authorized Chevrolet dealership.
Assuming you did nothing to disturb the timing it would not have to be reset just for changing the head gasket.