About the thickness of speaker wire...go to this site http://www.bcae1.com/
and go down to number 16 on the right hand side which is "Wire." Once you get to that page, there is a calculator that will tell you how thick your speaker wire needs to be to not create an audible difference. You will probably be surprised...a lot of people who think they are so "smart" and get really thick wire don't need it at all, it bothers me :P.
Check it out, nice calc, nice site.