Salt is considered to be a regulator of the fermentation process but I don't know if reducing it from 2.75% to 2% would be enough to cut the time from 24 hours to 12 hours. I am talking here of a room temperature fermentation, which is typical of the methodology used in Naples. I would think that increasing the amount of yeast would be more effective than reducing the salt levels.
The above notwithstanding, I think it would be useful for you to try to find the "W" number for your particular 00 flour since that is a pretty good indicator of its intended fermentation time. That won't be the entire answer since you have to balance that with the amount of yeast and salt and the fact that you are using a cold fermentation.
I believe the answer to your overkneading versus underkneading question will turn on the particular brand and type of 00 flour you are using and also the equipment you will be using to knead the dough. 00 flours can vary quite widely in terms of protein/gluten levels and their quality and some will require longer knead times than others to develop their small amounts of gluten. The type of mixer (diving arm, fork, spiral, planetary, etc.) will also be a factor.