Interest rates do vary but they will never be more than 8.25% for federal loans. Right now they aren't great. If you can afford to wait, you might want to.
As far as information about consolidating, go to any of the lenders websites and they give you all the information you need about the process. If your lender doesn't do them, or you are willing to go elsewhere and have never consolidated before, you might want to shop around for a better interest rate. Some are higher than others, some charge fees where others don't, etc.