Check chapter 2 of the manual
In FM Synthesis, you often refer to an oscillator as "operator".
Shape :
This define the waveform that the oscillator is creating. Pure FM snthesis only use sin waveform.
PreenFM even propose a noise (rand) waveform very usefull to create percussive attack or to add noise to your sound.
You can chose for each operator independently between sin, saw, square, noise and 3 sinus variations.
And the line just above this one answers your other question:
The available filters are (in firmware 1.04) : Low pass 2nd order, High pass, Bass boost, Band Pass and crusher.
Be aware that there is only one filter, you won't trigger a filter per voice, each time you play a key the envelop of the filter will trigger with all the sound getting through it.
The code of PreenFM2 is available so you can definitely mod anything you want if you have the skills.
