That is correct, the drive shaft and any other interference is removed and the battery is lowered out of the truck from the bottom. There is not enough room to work on anything if you remove the bed. I prefer taking the battery out, for the room, lighting, and safety.
Yes, all dealers that are EV certified will have all required test equipment, connectors, lifting equipment and most of all trained certified EV technicians (I myself am 1 of 3 at my dealer). We also have DC charging plugs outside the service bay, and 2 inside the shop, in my dealership we are...
No, it's a sealed unit; there is a procedure to conduct a leak test on the battery. The front and rear drive units can be tested from the degas bottle.