1) If the contribution is non deductible, Form 8606 will show 6000 on line 1, the same amount as the original Roth contribution.
2) Correct. The box 7 code should be “R”.
3) The 5498 reporting the Roth contribution will not be corrected, but the Roth custodian will issue the 1099R described above. There will also be a 2020 5498 issued for the TIRA account showing receipt of a recharacterized contribution of 5800 in Box 4.
4) Correct, a 1099R will be issued for the TIRA reporting a distribution of 5800, and a 5498 issued by the Roth custodian reporting receipt of a conversion contribution of 5800.