Traditional and Roth Contributions - are these amounts on the W-2 under box 12 (D and AA) that I should be reporting in the deduction and credits section?

No, please do not report contributions (reported on your W-2, box 12, D/AA) as a separate entry in Turbo Tax. All you have to do is report W2 data in Turbo Tax exactly as it appears on the form.

The retirement plan contributions you elect to make come directly out of your salary. Since the contributions are made with pre-tax dollars, your employer does not include these amounts in your taxable income for the year. At the end of the year, when you receive your W-2 form that shows your earnings, you will notice that your wages subject to federal income (box 1) tax are lower because of your retirement plan contributions (box 12). Since the contributions are not counted in your taxable income to begin with, you do not take a deduction when you file your return.

The Deductions & Credits section is for the after-tax contributions.