Interesting. The first code is almost always a blown clutch pack as your specialist said, hence no drive and limp mode. However, the second two are very unusual and indicate an electrical issue causing the slip. They would certainly trip limp mode, and the bang in to gear while in limp mode is pretty normal - in limp the TCU basically just gives up and the gearbox works purely on fluid pressure with very little finesse.
The first things I would do are:
Examine and clean up the big round connector on the bottom front left corner of the gearbox - make sure there is no schmoo or corrosion in there, and its all nice and clean.
Then, open up the electrics box in the passenger side rain tray and have the same good look at the TCU connector.
If both of those are clean then its time to pull the sump and test / replace either the internal harness or solenoids. I have both spare from blown up gearboxes.
I reckon there's a good chance its saveable
