"I reported adjusted gross income of 6,110, with EIC of 461, yet it let me contribute 6000 to the Roth."
AGI is not the limiting factor. If a $6,000 Roth IRA contribution was permitted and your only compensation was from self-employment, it seems that your net profit on Schedule C was at least $6,456.
EIC has nothing to do with this.
""which dollars" comes out doesn't matter, but rather it's the total excess plus its earnings?"
Correct. Attributable earnings are calculated using the entire account value, not any particular investment within the account. CFR 1.408-11 specifies the method for calculating attributable earnings. It's not straightforward, so the IRA custodian normally does the calculation when you request a return of contribution before the due date of your tax return:
https://www.law.cornell.edu/cfr/text/26/1.408-11
If you don't enter the contribution into TurboTax, it you might never realize that you made an excess contribution. The tax code was recently changed by the SECURE 2.0 Act to create a statute of limitations on a failure to report an excess IRA contribution, but this change only applies to excess contributions made after December 29, 2022.
You are required to include on Schedule C all of your business income and expenses even if the income is not reported on any Form 1099-NEC or 1099-MISC.
In step-by-step mode you should go through all of the guided sections. In sections that don't apply, you'll have nothing to enter and they won't affect your tax return.
As self-employed, unless you are confident that you will have enough compensation to support the IRA contribution, you would normally wait to make your IRA contribution until after you have allowed TurboTax to indicate that the amount of a contribution you enter is not an excess contribution. In other words, complete at least the self-employment and IRA contribution sections of TurboTax before making the contribution.
