Hey there Steve, Welcome to the club.
I see you are jumping in with both feet to do diagnostics. If you haven't downloaded it yet, get the service manual from the link I posted a while back. Here: viewtopic.php?f=14&t=4921&p=32331
Good move to pull fuse #3, (if I am remembering that right), however if that is the orginal 12V battery, it probably would not hurt to put in a new one. See my post about replacing the very expense group 67 with a much cheaper 26R. Here: viewtopic.php?f=15&t=4938#p32447
Probably no need for a level 2 charger, unless you want the convenience of a faster charge at home. Level 2 doesn't have to be hard wired. I use an adapter with my dryer outlet and a Tesla charger. I think it was recently discovered that the charger supplied by Ford can handle 220-240VAC. I can also use my BMW level 1 or Fiat level 1 charger, as they too can charge at 220-240 VAC.
Good thing your car got the splash cover retrofit. Mine was not part of the recall, but I did it myself anyway. What could it hurt. Important tip, do not put dielectric grease on any HV contacts, you will be asking for trouble. Just keep them clean, and tightly secured. Then put the grease, (if you must)at the gaps where the connector halves meet. Not really necessary, as the connectors are waterproof.
I believe one of the OBD ports has logic behind it, for interfacing with a VCM. or something more.
I understand your want to change fluids, but coolant and gearbox fluid probably aren't necessary. no rust to deal with, and no shifting parts. Yes, the gearbox is supposed to make that whine. Its how the gears are cut. There is a coolant filter, but it is pricey.