A slightly low coolant level won't effect the running temps as it's the computer that turns the fan on and off according to internal sensors. It's only a worry if it's way below standard level.
You can add coolant and your user manual should have the instructions. Purging air from the system is only necessary if the level falls very low or if it's being changed for new fluid. The Scout gets an air lock somewhere under the tank and it's this that causes the need for purging. If you are concerned about the temps, you are mostly feeling the heat from the radiator when the fan turns on, you can scroll the readout to show the coolant temp. I forget what it's on/off settings are but my Scout used to run very hot in summer traffic in the city. It worried me for a bit but didn't worry the motor. The PVCX or PV3 has a setting where you can lower the temp at which the fan turns on and many people set his up as a standard procedure when flashing a new tune to the bike.
From Woodrising (no, nobody else has heard of it either) Rides a Springfield Dark Horse