There's no real "user manual", but here's a lot of info floating around like here and here and here..And there's EVGA on the Tube with info about PrecisionX and other good stuff..Some of the info is a little dated and may not apply to your specific card and the newer versions of PrecisionX, but the basics are the same..You can also hover your mouse cursor over many of the settings for a pop-up of a brief explanation providing Show User Interface Tool Tips is enabled.The only thing I would recommend against is overvolting the card..You can overvolt it, and many people do, but that may end up doing more harm than good..You'll see a warning pop-up when overvolting telling you that overvolting may cause damage/failure and to do so at your own risk..If you overclock the frequency too far you'll just get artifacts, freezing, crashing, maybe overheating to the throttling point, etc. which you can recover from with no real damage to the card..The maximum GPU temperature for your card is 95C..You can set up a custom fan speed curve to help keep GPU temp down. 

No problem, and welcome to the forums..You can make a custom fan speed curve so that the fan speed ramps up faster/at a lower temperature that what the NVIDIA driver does on it's own..You can override the stock fan speed curve so that your card runs cooler with less thermal stress..It's up to the individual to balance fan speed, noise and temperature, but I have mine set to 100% fan speed at 70C with a 1000ms Fan Speed Update Period, which is extremely aggressive, but I have headphones so it doesn't bother me at all..Actually my curve is 40% at 40C, 50% at 60C and 100% at 70C..Personally I would go with 100% fan speed at no more than 80C/85C if I wanted to go a little less aggressive, just my opinion.
 
When increasing the core clock, there will come a point when extra voltage is neccessary to maintain it and be stable, same as with a CPU..Just increasing the voltage will result in a slightly higher boost clock speed due to the way GPU Boost algorithms work, but that's not the way to go about it and will gain you basically nothing to speak of as far as FPS goes by just raising the voltage..Raising the offset is the way to go..Personally, I would not overvolt.

No problem, glad to help.