The heater will start and stop running based on the water temperature the IntelliConnect sees to mainatin the heater setpoint in the IntelliConnect..
No, If your heater requires AC power to operate it needs to be connected to a circuit breaker.
The Firemans switch is a low voltage switch.
The NEC label on the heater says 120/240/24V (https://www.royalswimmingpools.com/rp2100manual.pdf) but was previously connected from the old Tork timer to the fireman's switch on the 240V/20A line. That would enable power 9-5PM and I'd adjust the heater up/down. Now, I will set it to max temp and IntelliConnect will just constantly enable/disable power to it. However, the IntelliConnect Heater only outputs 24V but that seems to be inline with the NEC.
And, Raypak doesn't offer phone support for residential. Sigh.