Questions about starting an online consulting business

Hello.  I am interested in starting an online consulting business. I would consult with clients via email, fax, phone, and/or Skype.  It would be a sole proprietorship.

1)  If I used my own name, I would not need to register with the state, is that correct?  If I used a fictitious name, then I would need to register.  Can someone please confirm this?

2)  Also, what other filings do I have to complete, in addition to filing estimated self-employment tax 4 times a year?

Thank you for your help!