New to Agency, Info Please!!

Hi,
I am thinking about doing some agency work on my days off as a way to make a little extra money. I was wondering if there are any agency nurses in the Chicagoland area that can offer me some advise and insight. First off, how much can I expect to make an hour? If its not much more than what I can make picking up extra shifts at my hospital, I probably wont want to drive further away spending more on gas to work at a hospital I am unfamiliar with. Secondly, is there any introduction into a hospital you are assigned to work in or do they just tell you when and where to go and you are left to figure it out on your own? If anyone can help out it would be greatly appriciated. Thanks!

~k