Parameters are accessed with C4DAtom::GetParameter()/ C4DAtom::SetParameter(). See page_maxonapi_getting_started_foundations_cinema_parameters.
Parameter: Grid Size
FFDOBJECT_SIZE
Parameter: Grid Points X
FFDOBJECT_XSUB
Parameter: Grid Points Y
FFDOBJECT_YSUB
Parameter: Grid Points Z
FFDOBJECT_ZSUB
Parameter: Fit to Parent
FFDOBJECT_FITTOPARENT
Parameter: Reset
FFDOBJECT_RESET