1) Doesn’t matter. The pre-trial conference will let you try to work out a deal with the prosecutor before the trial, but you can do that on the day of your trial as well.
2) At 30+ over, yes, you’re getting demerits if you’re convicted. But unless you’re close to a license suspension due to multiple tickets, the demerits are pretty meaningless. Any conviction for speeding will likely have a similar insurance impact, until you get up to 50+ over.
3). Until you have disclosure, there’s no point in thinking about what to say in trial. Keep in mind that unless you find a flaw in the evidence, you will almost certainly getting a conviction, assuming the officer shows up (which he’s paid to do). Even if there is a flaw, you’ll be arguing against a system that is heavily weighted against you. The prosecution proves their case by basically having the officer testify he saw you at location XXX doing a speed of YYY. That’s all the evidence they typically need. It then falls on you to discredit their expert witness. And the prosecutor and officer have been doing this day in and day out for years.