Not Jim, but I answer anyway with my knowledge and experience:
1) No problem.
2) Auto-regulation is always good, but you can also choose solid reps/sets (5x5 for ex.). I personally have done solid FSL with reducing the volume after each 6 week block: 5x8 -> 5x5 -> 5x3.
3) Sprints are taxing, specially with TM PR, but I have only done sprinting occasionally aside lifting and cannot say anything or sure. Your body will tell you a lot and prob. you'll feel like crap anyway for the first weeks.
4) I would recommend doing the first phase first. TM PR is amrap set with around 85-95% of your real max and that's not a joke. I would use the second phase as a peak for 3 or 6 weeks in 5/3 "cycle".
If you're really into challenging yourself just do the challenge - as its written.