You are not actually moving to Perth, but to a city 70km away, bit like saying I am moving to Leicester but living in Birmingham. Keep that in mind when thinking about the commute to the city for work or social events - theatre, sports events or just a night out.
Schools - go on here - type in Mandurah and you can check out the schools. Click on Naplan, results in numbers - green means above average, red means below. http://www.myschool.edu.au/
A few of the primaries are very poor so choose your suburb carefully - and the state high schools also perform badly, lots of folk on here who live in Mandurah opt to go private.