Buy them from ren, they already have bearings in.
ALl you need to do is remove the 2 17(iirc) from the caliper, remove handbrake cables, pull off the caliper, tap out the centre cap, 30mm nut in the middle, and then it'll come off. then once refitted, dont put the handbrake cables on, make sure the levers are right back, and pump the pedal, this will adjust the handbrake. then put the calbes back in and all done.