1. It's supposed to cover the entire emission control system, although obviously the lack of specific mention is a concern.
2. Actually, according to the EPA, 150,000 miles is the defined useful life of the emission control system, so this actually goes beyond that. Obviously, there is not (or had better not be) a countdown timer that presses "self-destruct" at 162,001 miles.
3. In this case, they are covered by a 5 year 60,000 mile warranty from the time of completion of phase 1 which then resets and starts again at the completion of phase 2.
4, 5. OK.
6. No, unless something malfunctions to the extent of triggering the lemon-law out.
7. That's nice. You are still covered by the 5 year or 60,000 mile (whichever comes first) from the time of phase 1 fix which starts over at the time of start 2 fix. Warranties have a time limit and a mileage limit ... that's life.
8. Yes, it does.
9. The useful life of a Toyota's emission control system is defined to be 150,000 miles (for Calif) or 120,000 miles (elsewhere). As mentioned above, there is not an automatic self-destruct when you exceed this.
If you can't handle the uncertainty then do the buyback and go buy something else that you're not as worried about.