G'day ajmuzza,
I think that the internals of the controller has an alarm output for high/ low temps. Which is what e1 and e2 are. The default values should be fine.
I am not sure if you are asking for a description of hysteresis or not, but I will include it anyway.
If you set 18C as the set point with a 1C hysteresis (and assuming you have the 16 amp controller with cooling and heating plugged into it) the controller will start cooling when the temp probe reads 19C and will cut out at 18C, it will also start heating when the probe reads 17C and stop when it reads 18C. So it will keep your fridge at the set point +/- the hysteresis (not accounting for any temperature inertia). However the the 10 amp controller will only heat OR cool depending on what you have plugged into it.
I have one of each. The 16 amp one controls my fermenting fridge with a heat pad on the lower shelf, while the 10 amp one controls my keezer.
Regards,
Andrew.
Edited to add some additional detail.