Yes, you can jack up the 6-cylinder using the oil pan, no problem. Just be careful and unhook the motor mounts first; don't try to jack up the whole car with the oil pan -Ha. Yes, you will need to raise the motor a bit to slip in the motor mounts. Unhook the air intake and check the hoses and wires for binding as you ease the motor up an inch or so.The right mount is the first to go, as it is torqued downward when the engine is under load. This can cause the exhaust to rub on the cross member, makes a terrible banging noise.
This may be what you are hearing on that side.
Another noise-maker is the guide rod bearing. they clunk loud when tapping the brakes or going over small bumps. Search herein for how to replace them - not too difficult.

The tranny mount is on the very rear end of the tranny shaft - just a couple of bolts, put the jack under the tranny first of course. You can't usually tell if this mount is bad, it just sags a bit. cheap and easy, just do it.

The front flex disk is pretty easy; because there is room to work it out without removing the driveshaft on the 126 (that's a real pain). I'm not sure if other models can be replaced without removing the shaft.
The only trick is getting the disk in correctly, and the right bolts/washers in the right holes, etc. There is writing stamped on the disk in German, that says "this side to the rear". Then the bolts are different lengths. Just really look over the old disk and how it's mounted, and make some notes on bolts, positions, etc; and it's no big deal.

if the mounts don't fix things, it's possible you could have a driveshaft center bearing going bad. in that case you will have to remove the entire exhaust, and the heat shield, then drop the driveshaft - lots of work, but pretty straight-forward.

DG