All the questions you described look like those that apply to Traditional IRAs.
my first answer above was with Traditional IRA in mind.
Since TurboTax knows it is a Roth, maybe it asks similar questions,
but the calculation would be (or should be) different for a Roth, as you point out.
(The total value of all Roth IRAs at year end does not appear to be relevant.)
Sorry for any additional confusion caused by me jumbling Roth IRA and Traditional IRAs together.
