You are correct that a reboot will trigger a full rescan. I'm always on the lookout for better sync. I just don't think it's out there right now for easy bidirectional sync.
Basically, if you want to set and forget, Syncthing is the best option. If you want more control, you'll need to look into setting up rsync scripts or similar, which will at least better let you control how often to sync.
Because it's probably bullshit. Elon Musk is a colossal problem, so people feel justified in whatever lies come to mind.
The Cybertruck has steer by wire BUT NOT BRAKE BY WIRE. No other Tesla has any such system. The brakes in all Teslas are traditional.
The question of who pays when you have an accident with autopilot has basically been settled in court: the normal rules of fault apply. If autopilot is at fault, then you're at fault. If you're in control, and you're at fault, then you're at fault.
The idea that an insurance company says, "Oh, we won't cover it because you deactivated autopilot" is outright silly. Ignore the autopilot thing for a second. What happens when you rear-end someone? Your insurance covers it based on your coverage, and your premiums probably go up significantly.
The driver was supposed to be in control, of a vehicle with traditional brakes, and hit a car. If they have coverage, it should be handled just as if autopilot weren't involved at all unless they can prove that Tesla is at fault.