Good info has been given here, however, there are some little known facts....
You can deposit checks written to a business in your personal account through an atm and if the check is under $1000.00 a human will not see it in most cases. This does not make it right and there is a chance of a human rejecting it but over $1000.00 sends a red flag and they will not process it. You are MUCH better off to do it right and set up a business account.
Spacedog is correct about the EIN. For a sole proprietor they will use your SSN. If you want to get an EIN for tax purposes, the IRS can be a pain in the ass. You need this form:
http://ftp.fedworld.gov/pub/irs-pdf/fss4.pdf I suggest checking the box that says you intend to hire employees. This will get an approval for an EIN almost every time.
Different states require different paperwork to register an Assumed Business Name or Doing Business As name. The best place to find this is with your States Corporation Division. Most states offer the forms online in PDF format.
FYI... I spent 4 years as a Trainer and Supervisor at Wells Fargo. This info is from my personal and professional experiences. If you need any assistance finding the info for your state, feel free to hit me up on ICQ. I have most of the stuff bookmarked.
Good Luck
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