Yes, Ireg makes sense here and bQ1 is beta. They basically tell you to subtract base current of the PNP from regulator current and select a resistor which provides that much current.
Ireg should be selected to be no less than the minimum load current for correct operation, under all possible conditions. Besides that, I think just about any current will work here. If you keep it low enough, you may get away without heatsinking the regulator in some cases. (Note that if the transistor fails open, Ireg will increase to maximum and the regulator will start to cycle between full power output and thermal shutdown.)