The reason you get a DBA is so your bank will cash checks payable to "Cool Internet Company" and put the money in your bank account - without brain damage to you.

Apply for an EIN. Otherwise you will be spraying your personal social security number all over the place.

Your income and expenses go on Schedule C of your tax return. You pay income tax on your profit and you also pay self-employment tax. If you do well, expect your tax bill to hover around 50%.

Disclaimer - IAAL but all of that stuff I just told you is off the top of my head and probably wrong. Call up your local bar association. They probably have a referral program with cheap initial consultations.

Get a good accountant. If you are in San Jose on Dec 11 2014 attend the CalCPA Startup Conference and schmooze. http://calcpa.hs-sites.com/startup14-hacker

The chief reasons to get a business bank account are a) if you're going to invoice larger companies it will make getting payments rather easier (you appear to not be doing this) and b) it makes it marginally easier to segregate business and personal finances, which will simplify your tax compliance.

I didn't have a separate business bank account for, hmm, ~7 years. It is skippable.