No need to replace the ring gear if the replacement looks as good as your old one. You really don't want to mess with the ring gear. Consider that the starter spins a cold engine through the interference fit between the ring gear and the starter. It's going to take more than a nautical vocabulary to get a ring gear off an another one on.
If you don't tackle the ring gear, the only special tool you might need is a degree of rotation measuring tool. I've never seen one but you can probably get one at any auto parts store since many cars have degree of rotation specs for final torquing.
I painted a line on my socket, painted a mark at 90-degrees near each bolt (relative to the line on the socket, of course) then eyeballed it. The key is to turn in 90-degrees in one step.
I don't know what bearings you can replace.
Is the flex arm that 3-arm plate that the torque converter bolts to? It should be easy to tell if the old one has any damage. I think it was a $30-40 part new.
If your transmission has never been off the car, the bolts won't be too tight. MB has very light torque specs compared to other cars. You should be able to loosen the bell housing bolts with little more than a combo wrench and a good grip.
The flywheel bolts are a different story. I used an electric impact wrench to get them off. You can rent one for $10-15 a day.
Jack stands will get the front end high enough.
You might balance the flywheel when you attach a new ring gear. If you use an old flywheel with ring gear, it should still be balanced.
When you pull the transmission, the manual says to mark the flywheel and torque converter so you can put them back together in the same orientation. When you replace the torque converter, it doesn't say to get the flywheel and new torque converter balanced. The advise to mark parts going back together is probably there to minimize the chance of introducing imbalance, but I think chances are you won't introduce any if you don't get them back the same way or if you replace one part or the other.