If your business is a sole proprietorship (which is what I assume since you mention a DBA) to register for a state tax ID go to Texas Online Tax Registration Application

That is NOT the same as registering your DBA, which is done at the county clerk's office.

Opening a bank account for a sole proprietorship varies somewhat from bank to bank. Talk to your local bank.

You can go to the county clerks office, and register your DBA. I think it's still a 15$ fee.

You can probably do it online, depending on how rural an area you are in.

<--lives in texas