The frame is specific to the Lightning, but it's a modified ICE frame. Every stamping of the cab is the same as ICE. The only part of the bed that is different from the ICE truck is the outer bodyside. The XLT and PRO tailgates are from the ICE truck. The rear bumper is the same as ICE.
The age of the house does not grandfather you in. Yes, you don't have to bring it up to code. But you will if any of your remodel moves the circuit in any way. It's the same with GFCI in damp/wet locations, and Arc Fault requirements.
The truck is not grounded. And if you remove the ground from the cord, or from the panel, you have no path for fault current back to the source.
It seems a lot of people don't know the difference between "ground" and "bond".
You're trying to make sense out of something that doesn't.
Drive your truck and enjoy it. Unless you don't have the battery percentage on the IP, you're not missing anything important.
Mostly surrounded. But it doesn't matter. I wish there was an adjustment for it. If I replace the rest of my speakers and add some sub, I might just unplug it.