How often does the shuttle comes?

Around every 15 minutes is your waiting time...Very Reliable

Agreed. Even after 10 pm the run about every 20 minutes. Just make sure you are on the departures level; they don't pick up on the arrival level. Great service.

It depends. During busy periods more busses are running. At those times there is little need to call. But at times when you see few passengers in the airport, there are probably few buses running, and therefore it would be wise to call or text them to do a pickup. When you do ask for the pick up you'll want to give them the number of the exit door you're located near on the ticketing level