If I owe self employment tax, is that included in this TurboTax return or do I have to mail that check separately? Or is that already being reduced from my return?

If you owe self-employment tax, TurboTax has calculated the amount of self-employment tax due and included it in your tax return. The amount due (or refund) shown on your return already includes your self-employment tax due. You do not have to pay self-employment tax separately.

It is included in your total amount due