removing the caliper is easy, you should figure it out. and yes I would do the job myself than paying someone for a simple task. pads need to be filed at the ends. the shims are some 0,5 mm thick metal plates that are positioned in the area where you will need to file the pads. general opinion is that you'll need to remove these(use a flat screwdriver to get them out if they don't come off by hand). file the pads down until they fit easily in the carrier and have a little play (in a vertical direction)-about 1-1,5 mm. you will also need to push the caliper piston back in as the new pads are thicker and the caliper won't close otherwise. I managed to do this using two spanners, one rested on the piston, the other used as a lever(easy to figure out how to). mount everything back, job done