#3 is so nice, I want root access to my phone. Does anyone know if doing this can lock Apple out from updating/removing it?

Subverting the secure boot/upgrade chain would require a SecureROM exploit and presumably a compromise of the Secure Enclave, so the answer is almost certainly "no" (even prior major exploits from recent memory like usbliter8 are tethered and don't exploit the enclave; the last true untethered Jailbreak was iOS 9 or something.) An upgrade would fix it. The internet reporting claims this break they are showing in this video is untethered though, which is extremely rare on its own.

The videos sort of imply that these are userland rather than bootrom, whatever payload they have running is getting hit before first unlock, which isn't a lot of surface. They specifically say to not update which pretty much confirms where the attack surface is. Somewhere after the kernel starts but before the main user space is unlocked with the passcode.

Well the governments and supranational bodies who want to read your messages would be aghast at you having root on your phone.

Like we did on HTC G1s in 2008