I'd say a PPL gives little to no advantage in the selection process. It does however help during the foundation phase of flying training as well as during Ground school. The PILAPT/Cut-e tests i would almost advise against getting. I have heard horror stories of someone who bought one of these aptitude tests and religiously practised on it. When they did selection they found that the joystick section gave different inputs to what he/she was used to and consequently found it pretty difficult!
Good Luck!