The bolt and washers are to use instead of buying a tool. Once you have used that stuff <<<<< to crimp the nutsert then you can use the M4 fasteners of your choice to hold the flap.
You might have to drop the blower motor and hamster cage. It sounds like something has dropped in there when the filter was changed.
I had to get acorns out of mine once. IIRC it involves undoing three screws and unplugging a plug. Fiddly but not hard.
Backing up can be a challenge so plan "drive throughs" to eliminate having to reverse.
It is likely the Uhaul guy or girl will hook the trailer up for you, watch them, and then double check everything yourself. Drive a mile or two down the road to somewhere you can pull over and check everything...
Easiest is probably go to the dealer and buy a fob, cutting, and programming. It cost me about $300 about 6 months ago. You will need proof of ownership.
The question that comes to my mind is, Is there a difference between two and four wheel drive springs? These days truck makers economize as much as possible and with the ride height appearing to be the same 2/4wd I wouldn't be surprised if the springs are the same.
It would appear that the seal went out on the previous owners turbo. Now you've cleaned it out you should be good to go. Not something I'd worry about as long as there were no chunks in there.
Murphy's is local and usually cheapest, they also have a pretty good rewards deal so that is where I usually fill up. Another bonus is that they are pretty busy so it is unlikely I'll get bad gas there.
I will not buy Shell unless I have no choice. I am not sure if they have changed the formula...
I traded a '10 Sport Trac for my '19 XLT FX4 SCREW which I traded for a Land Cruiser which I traded for a 22 Tremor, then I had a couple of Jeeps, a Gladiator and a Grand Cherokee and now I am back in a '21 XLT FX4 SCREW. I like this one the best.