Umarex Tuning regulator and hammer spring (Umarex Zelos)

I’ve read a few posts on the topic, but am still trying to wrap my head around these concepts and information.

From stock settings, what would I need to do to tune down the Zelos? I was hoping to drop down to 1800-1600 in order to get more shots and to lower the FPS of jsb Hades closer to 850-900.

Few questions to go with this. Is it possible to hurt anything by taking the hammer spring too far in or out? If I lower the regulator to say 1800psi, should I set the hammer spring all the way in or all the way out as a baseline and increase/decrease little by little until gps stabilizes?

I hope this makes sense. My first PCP. Just wanted to get consistent shots with lighter pellets for iguana hunting and hoping to tune down a little. If anyone has good resources or videos to help me better understand this stuff it would be greatly appreciated.