This might be true for the KEKs (key exchange keys). But the PK (platform key) will be already set up (and controlled) by the hardware manufacturer if I understand the system correctly. With UEFI you do not own your hardware anymore.

No. It is designed to generate a chain of trust from the BIOS (UEFI) up to the operating system including drivers. So if you change anything in this chain, DRM-plagued media will refuse to play! It's all about the ability to play content withot the user being able to grab that content or do anything else with it. If it would be about preventing root kits, then the master keys could be in the hand of the user.

I toast, therefore I am!

Heuristic simply means that your algorithm is not 100% correct. Top level human chess players use heuristics to play, they do not calculate all possibilities. Doing things by heuristics means guessing (and hopefully guessing right most of the time),