Congrats!
Most owners who change their own oil use some form of suction to remove the oil via the dipstick tube. But there is a drain plug on the pan for the old school way.
Since access to the oil filter is on top of the engine as well this eliminates lifting the car.
Most MB technicians are pretty thorough. I would think that if they serviced the transmission they would look for common issues. If you have the service records you can review any comments. They will tell you if they spotted a problem but the owner declined to do the repair.
The 722.6 transmission has a very good reputation and was used by MB for V8's and the V12 engine.
I've never found a service cycle recommendation for the fuel filter.