Well, I think your heavy days are laid out fine. Working in the neighborhood of 6-9reps should put you in the neighborhood of around 75-85% 1RM, and with these inroads into your CNS, you could easily do with about 2-3 mins rest between sets A seond workset might not hurt either. When I was into the PL thing about 15-20 years ago, we used to plan our workouts by %'s and rep goals for the day. Say we were working 85% of 1 RM for a top set of 6 reps. rather than busting butt and repping out doing more reps, or doing multiple sets of our top weight with 6 reps, we would do the warmup (or 2 if needed) and hit a top workset (very close to maximal) and then do another set of 3 with the same weight, then a set of 2 with that same top weight. Didn't beat up the CNS as much, but going with one maximal work set as you have planned will work, for a while anyway. It's an adaptation of HIT, and some swear by it.
Now, the light days, 10-15 reps, a couple of sets will probably put you in the 65-70% 1RM range, and won't make hard inroads into your CNS recovery time, so 60-90 seconds should probably be sufficient.
Auxilliary exercises. Well, they can be beneficial. For a PL type that's interested in Sq, BP, and DL, some of them won't be as necessary, but it's really up to you to decide. If you've got enough gas in the tank, then throw a couple in with the main exercises and see how it goes