I picked up a new intense spider late last summer love everything but the juicy 3 brakes so I got some Marta sls but one rotor is 160, what was on the bike and another is 180.

can I run different size rotors? Or what if I leave the existing rotors on, avids have a smooth outer edge but the magura's are wavy

also are the washers for the rotors or to shim the brakes out so centered w/ rotors or washers for the rotor mount ( 6 came w/ each brake)

thanks