On grammatical class:

mu'e
abstractor: achievement (event) abstractor; x1 is the event-as-a-point/achievement of [bridi].
pu'u
abstractor: process (event) abstractor; x1 is process of [bridi] proceeding in stages x2.
za'i
abstractor: state (event) abstractor; x1 is continuous state of [bridi] being true.
zu'o
abstractor: activity (event) abstractor; x1 is abstract activity of [bridi] composed of x2.