You are correct no gasket between exh pipe and manifold.
How many miles on the car? Because the pipe seperated easily from the manifold on mine. It will drop 2 or 3 inches if you loosen the 4 bolts on the trans mount with exhaust hanger....no need to remove.
The hard part is getting the old manifolds out and the new headers in as the engine needs to be lifted 4 or 5 inches and a small boy with small stong hands can set them in place and tighten the bolts. Or you can lift the engine a little farther and replace the motor mounts and headers without the small boy. (your choice). I am going to go out on a limb here and say most likely your motor mount is broken as I have replaced 3 and finally fixed the issue by cabling down the motor and have no further problems with broken mounts. The trans mount will need to have you support the trans while you replace it. A good roll around jack with a 2x6 between the saddle and the trans pan will keep from denting the bottom. The sensors have enough play in the lines to not be removed if you just unclip them from the mounting clips if you don't want to mess with unbolting them. I thrash my car a lot and have never had an issue with the drivesfaft bearings. I have not heard of much trouble with them but if you are intent on replacement be sure to clock the shaft and all related components ( mark a line through all mounts and spacers between all the pieces) nothing worse then getting it all back together and having the vibration from an unbalanced intermediate shaft. Those are all balanced from the factory in the positions they will be residing in the car so keep it straight and you should have no issues.
I have a set of the VRP headers and the motor mounts need to be raised 1.5" to clear the frame etc......a plate between the motor mount and the frame would work or just fill the mounts with poly and they rest higher then with the hyd fluid so that could work as well.
Good luck ....take lots of pics along the way.