Could you tell me ideal pressure for my staggered tire?

Hello, it is always recommended to follow the placard on the driver's door area for tire pressures Ford has mandated for the vehicle. If you have changed tire sizes, it could change things, but I would say it's a good guide.

Second question answered -- You have a lot of torque going to the rear wheels and rather light rear of the vehicle, weight wise. You will get some breaking free of the rear axle and rear wheels if you're not careful and surfaces are slippery. Traction control can help, but learning how to best operate your vehicle will too. Sure, wheel alignment can play into tracking, but this sounds like good old fashioned low end torque.