Info for New Chain/Sprockets

So as a bunch of you know already, I have been blacking out the rear end on my bike.  I took the chain off the bike that was on it because it looked like the original chain and my bike's an '04 and it was rusted from sitting in this guy's garage.
 
Anyways, I was wondering if it was possible to get a chain and/or sprocket in black to match what I am doing to the bike.  I sent the original sprocket off to get powder coated with the swing arm, but I was planning on just keeping it as an extra. 
 
I was also interested in getting black sprocket nuts to complete the look.  Can anyone help me out with a link?
 
Also, if someone could explain to me the difference b/t a 520 or 525 chain...I find it a little confusing (I think it's the pitch?) and I'm not so sure I get it.  Which one is better?  Is there that much of a difference?  Should I change my front sprocket if I am going from the original chain to an aftermarket one?  Such info would be greatly appreciated.

 I've got a Drive System, hard anondized aluminum rear sprocket in black. I would go with a D.I.D. chain no matter what. Not sure if black is even an option tho.

So I think I'm going to go with this set-up here...black/gold sprocket and gold chain...I really like the tri-metal sprocket, and I think I'll spring for it w/ the lifetime guarrantee.  Plus it's two colors, which should match the black conversion on my rear end and the gold chain I plan on using.
 
Info here: www.supersproxusa.com
 
All my chain questions were answered here: http://www.peterverdonedesigns.com/chainsandsprockets.htm
 
Which led me to know everything I could ever imagine about chains here:
http://chain-guide.com/

Check out vortexracing.com, they have black and thats what I am most likely going to use.