Wow, that tool is a serious looking machine. Yes, they can be opened from the back, and all the settings are in there, but they are put under a extreme amount of pressure afterwards to make sure that they are sealed. Rolex is a serious watch.
But I certainly cannot comment on how to ascertain a discount, except through a dealer..
Nor do I know how they adjust them. I love loev watches, but the inner workings are still a unknown boundary for me. I opened up a old watch from my grand-dad (RIP) and I slapped the back right back on.. Too complicated, too many small parts, too many things to mess up!