No. Eligibility for the earned income tax credit is based on income, not age. The amount of the credit varies with the number of qualifying children you have. A modest credit applies even if you have no such child; the credit amount (and the income limits for eligibility) scales up for one child, two, children, or three or more children.
Total business receipts reported on Schedule C or Schedule C-EZ before deducting adjustments for returns and allowances and cost of goods sold.