Yes, that's what I meant. If you look at the rate of acid production at the various temps, for most mesophilic strains, the upper limit of what the bacteria tolerate is 105 degrees. But keep in mind it doesn't stop the bacteria, just slows them down a little. If you used too much starter to begin with, it will not make a huge difference... might buy you an extra 10-15 mins of time.
Farmer, if you had raised it to 104, it would not have made a dramatic difference. In your case, you were fighting time. Bacteria and yeast have these peak periods where they are eating and gorging themselves and multiplying as quickly as possible. Because you gave them an extra half hour at a very comfy temperature, they really went crazy and multiplied. Effectively, it's similar to using 1.5x-2x the normal starter amount, especially if you used a buttermilk or active mother culture. I would say raising the temp is a helpful tool if you are trying to buy a little more time, just as you said if you're at 6.1 and the curds aren't quite there yet and are too moist.
With regards to the salt, it actually does slow down the pH. Did you plot pH drop over time? For example, from culture to whey drain is something like 45 minutes for a .4 drop in pH. This rate of change does decrease slightly after salting. But it's not drastic. At least that's been my experience.
Yes, you must mill at 5.4. If you get to 5.3 it's not terrible. You can also mill at closer to 5.5. You're looking for the right texture at milling. The cheese slabs should be solid, flexible, and if you pull on the end, you should be able to pull a string out, or at least a piece that doesn't crumble.
By the time you press, there's not much you can do about pH. You could slow it down a little by cold crashing the press, but then the curds won't knit. At press time, the game is basically over and now it's time to focus on brining (if relevant), drying, affinage, molds, etc. Any remaining lactose will be eaten right away in 12 hours or slower over the next 24 hours if the room is cool. Outcome in the final cheese is about the same. To put it more plainly, the cheese will do what it will do, and let it do its thing. Press so the curds knit.
This cheese should be fine if it knitted well. A lower pH at draining does help a little with knitting (less calcium phosphate in curds means more protein-protein interaction).