The vital bits are the row of 3 terminals up by the coils. I think the middle one is common and the outside ones for the individual coils.
The other bits are extra switches for ... whatever. Some modellers use them to disconnect the power after the machine is thrown, to prevent burnout. The heavy one can be used to change frog polarity. They can be used to control signals or indicator lights or relays that will control all sorts of things.
If you use the little feeler contacts for frog power, check that it breaks contact before making the next one, or you will get a quick short. The operating arm for this should have a bit o plastic insulation on it.
You could use the feelers to power an insulated section of rail beyond the frog in such a way that it is dead, rather than inverse polarity, when the turnout is set against it. Then the loco stops rather than shorting out when it runs against a closed switch.
One of the sets of contacts may be grounded to the switch machine. This may end up connected to track power, depending on how you hook the machine up to the points. This can give interesting shorts.
(Done from memory; my NJ switch machines are mounted under the layout right now.)