Before using FM12 turn the volume down as some patches might be loud.
I realize FM sound programming is a real groove busters but only good things come out of a little work. Let me know if you have any questions. Most of the info should be there but I may have missed something or the info is not clear. However to get started there are two thing you should become familiar with.
On the top right, set the cal to the cpu usage with no notes playing or simply turn off the Cpu button which reduces Cpu when a lot of notes are playing.
The second thing is in View B and is used to customize your Keyboard Velocity Curves to get the dynamics set properly. Play your keyboard soft to hard and adjust the curves to get the proper dynamics for that keyboard. There are 3 adjustable curves to work with, select one with the orange light and all adjustment are in a row. They are velocity gain, velocity offset, followed by two choices of curves; the log curve and the hyperbolic curve. I have a lite action keyboard and a weighted action keyboard. I use a different curve for each one. Recommend adjusting it with the basic Electric Piano patch.
Once these two things are taken care of, you are good to go. I'll check back periodically and try to answer any other questions but do this first before trying other snapshots.
One final note, 2 of the 3 demo's use FM12 to generate the "Sympathetic Resonance" of a sampled piano when the sustain pedal is depressed. Have fun!