This is more of a generic question but it is on my GS so...
The back rim was white, once upon a time.  Now it's covered with road grime, grease, and who knows what else.  
How do I make it white again?

Second question:
I have no doubt that the local stealership will want one arm and part of a leg to install a rear tire that I'm going to be due for very soon.  Is this something that I can install with home tools?  I'm fairly mechanical.  
They are tubeless tires, right?

clean it! brake and parts cleaner works well, but isn't too good for the skin. Otherwise, I have had pretty good luck with a toothbrush, some general cleaner (simple green, oil eater etc. ) and water.

If you take the wheel off of your bike, you can usually get a pretty good deal, even at the dealer. $25 ballpark for installation and balancing. Worth the money, in my opinion.

I use a product called engine brite. It works awesome! I think its petroleum based. Like I said works grrrrreat!

We discussed changing tires a bit last week:
http://www.gstwins.com/forum/viewtopic.php?t=10914

Set the page at clarity.net for more than you want to know about changing tires... then read the replies on this forum, for why that is overkill.  But it's still good to know what's involved.

I mostly changed my own tire because I'm riding $30 tires, and it seemed silly to pay $20 to have it mounted.

I took my tires off my bike and took them to a tire dealer.  They only charged me $15 for installation.  Call around for prices.  It doesn't have to be a bike shop to change a tire.

Simple green works great at cleaning rims, that's what I use.

I always take the wheel off the bike. If you are mechanically minded and can be bothered, there are a few threads on here about DIY wheel changing.

For cleaning the wheels, there are loads of products out there than will do the job.....but I have found a toothbrush and parafin does a wonderful job...any hardware / camping store should have it and it's dirt cheap!