I can only speak for the tower.
Rostered Staffing for consoles at various times:
0600-0615 - 3 controllers.
0615-2100 - 4 controllers (plus 1 on a break)
2100-2130 - 3 controllers
2130-0600 - 2 controllers
Shift manager rostered from 0630 to 2200 each day.
There is currently no shortage in the tower and there were 2 controllers on (as rostered) at 2200 on the night you mention. No idea why there may have been unusual delays that night.
Not sure if Airservices are recruiting at present.
It takes approximately one year in the learning academy (training college) and then about another three months in the tower to gain the first two endorsements (Ground and Clearance Delivery). Then there'd usually be a consolidation period on those positions of anywhere between three and twelve months before training for another 3 months on the next two endorsements (Tower and Coordinator).
The training and consolidation periods can be reduced if training a controller with previous experience as opposed to an ab initio.