I also moved from a TT and with the help of this forum it has taken almost a year for me to learn where all the important things are.
I would register the vehicle with Thor and have them send you the plumbing and wiring schematics.
Additionally since you have a passenger side bathroom there is most likely an additional holding tank drain valve on the passenger side under the bathroom. Some dealers like to deliver with them open, but it is best to close it. Closing helps improve dumping and relieves stress on that black pipe that runs under the coach. At the dump station I connect the hose, open the driver side valve, then the passenger side, and then the grey water. If your slide out controller is the same as mine it is located in that large luggage compartment on the driver side behind a panel with 4 screws. I have never had to use it but it is a good to know. Knowing how to manually close the awning is also a good to know. I got that from the Thor documents on my coach.
If it were not for this forum and Thor I would never know.
Oh and the hot water heater bypass valves can be found under the right side of the dinette behind the drawer that is there.
I have found a good RV dealer that is Thor approved in my area and a place to change the oil that is not a truck stop.....that depends on Ford Dealers that can service the E350 in your area. I am hoping that you have a good dealer. I did not know any better than Camping World, but I worked with Thor to find someone better and they were very helpful.
Aftermarket wise I purchased 4 of the Max Air roof vent covers and a surge protector and water pressure regulator to use at the campgrounds. The MaxAirs are nice, they make a little noise as they lift when driving, but they do not drill holes in the roof for them or at least the models that I purchased.
Oh and bought some good caulk and check the tire pressure regularly had to hand tighten some of the plumbing connections inside the coach.
Otherwise it has been a good coach. I thought I was getting something simple buying smaller, I have learned a lot. I cannot imagine having a 40 foot motorhome with that learning curve for my first.