New to contract employment and owning a business

Hello,

 

I have always been an W-2 employee until recently. I recently started a business, and contract work.

 

Here are some of my questions:

 

My wife and I have always filed a joint tax return. She is still a W-2 employee. What are the advantages and disadvantages of continuing to file jointly with her as a contract worker and business owner? Would we use the same form as before (1040?) if filing jointly? If I chose to file on my own, what form would I file with?

 

When hired for contract work, what are the advantages and disadvantages, tax-wise, of using my name and Social Security Number vs. using my business and EIN?

 

Here are a few other questions from the prewritten list that I'm still not sure about.

  • I started a new business, how does that affect my taxes?
  • How much do I need to pay in quarterly estimated taxes?
  • Do I have to pay quarterly estimates on income taxes to my state too (I live in Washington State)?

Much appreciated!