[Chris_Rogers]

Personally I would loosen all the wheel bolts and retorque before I repaced the discs unless you have another reason to change them.

I don't know about the ATE disks but the calipers on my car are made by ATE so it's a good chance the discs are too.

My experience has been with the rear brakes, I fitted the ATE pads from Europarts, they work better than the Volvo pads they replaced and don't squeel. My car did have the shims fitted though.