When replacing the rotors, it is advisable to put a THIN coating of anti-seize compound between the hub and the rotor to facilitate removal next time (the rotors can sometimes "rust-weld" themselves to the hub).

Setting the wheel bearing runout is best done with a dial gauge so that you can set the runout to the precise factory spec. Typical setup would be to use a magnetic base and holder with the dial gauge. Once you have the hub/rotor assy back on the spindle of the steering knuckle, tighten and back-off the spindle nut to set the bearings in position. Then, use the magnetic base to "grab" the hub/rotor assembly and setup the dial gauge to measure the spindle. Grab opposite edges of the rotor and push/pull the hub/rotor assembly in and out and watch the dial gauge to see how much runout there is. Gradually tighten the spindle nut until the runout is in factory spec (I don't know the spec for your car). Then lock the spindle nut in place with the allen screw.

This whole process sounds much more complicated than it actually is. Whoever sells you the dial gauge and base can probably show you exactly how it works.