If you know how to change the front you know how to change the rear. I can do it without removing the caliper by loosening the bolts that hold the pads and then sliding the pads out and new ones in. The real way is to loosen the rear axle and the bolt in front of the axle just below the shock and then the bracket that holds the caliper will slide around towards the rear and give you access to the caliper, then you can change the pads that way. As for the caliper being loose it is supposed to be snug on the bolt that holds it and not allow for allot of up and down movement. I seriously doubt that the bolt is out of round more than likely, I don't remember if its a spring or a oring that keeps the thing steady but you may want to take it apart and see what was in there. Mine is pretty much the same way and I really haven't done anything about it because it really hasn't bothered me enough. I have to change the rear brake now though and may address the issue. The springs that keep the tension on the pads is not the spring that will stop the caliper from moving on the support shaft. If you want a pic
here is the pic of the rear caliper in all its glory so you can see all the bolts.
http://www.hdlparts.com/fiche_section_detail.asp?section=148352&category=Motorcycles&make=Honda&year=2001&fveh=3470Hope this helps you may have to do a cut and paste on the address to work