This is just your basic information and emergency contact information, which I'm required to have on file.
This just lays out the terms of your working with me, what you will do, and how you will be paid.
This verifies that you are eligible to work in the United States.
This form is a request for a Tax Identification Number. Because you're a contract worker, not an employee, I will not be withholding taxes on you. This let's the IRS know that you are doing work for me, and that you will be responsible for paying taxes on your income.
This is an agreement that you will keep all business information confidential.