I pre-paid some 2016 taxes - would these payments be captured by my w-2? If not, how do I make sure these are noted on my 2016 return?

Those estimated tax payments would not be reflected on your W-2. 

To report your estimated tax payment(s) in TurboTax Online, go to:

• Federal Taxes
• Deductions & Credits
• Scroll down to "Estimates and Other Taxes Paid" Under “All tax breaks”
• Click on “Show More”, then Select "Estimates" Click on Start or Revisit
• Select the type of Estimate Taxes paid, for example "Federal estimated taxes for 2016 (Form 1040ES)"
• Enter the amounts of estimated tax payments you made and adjust the dates paid if necessary.

Looking for Estimated Taxes (1040-ES) for the current year?  To go directly to that section of the program:

• Type "1040-ES" into the search/find window
• Click on "Jump to 1040-ES, estimated tax for next year"
• On the page: "Adjust How Much Tax You Pay" answer Yes or No to "Do you want to change your W-4 withholding for 2016?"
• On the Review “Your Estimates Page?” click on Review Now
• Continue with the step-by-step interview to determine your 2017 Estimated Payments