I flew to Faisalabad from Islamabad a few years ago via PIA. The Plane was a prop-driven Fokker, and the flight only lasted about an hour. It's a good option to get quickly to the city, and shouldn't cost more than $50.
However, I don't think PIA flies to Faisalabad from Islamabad anymore. I do know that PIA flies to Faislabad from Multan and Karachi.
Before you get on the plane you will have to go through regular security checks, but these are standard.