1) The 3 year rollover option only applies to a corona virus distribution (CVD) that meets the requirements for such a distribution. If those requirements are met, those distributions can be rolled back over 3 years and are exempt from both the 60 day deadline and the one rollover rule for 12 months. This is done by deeming the rollover to be done by direct transfer (basically not counting the return of funds as a rollover). Therefore, this example is not impacted by the 2019 rollover as long as the 2020 distribution qualifies as a CVD.
2) No. Included in above explanation. A 2020 CVD in which the income is reported over 3 years is still taxable until the taxpayer reports the later rollover. The rollover after 2020 will trigger various options regarding if the earlier return is amended for a refund, if the current year tax due is reduced, or even a carry forward income reduction is elected. All this assumes the IRS Rules for 3 year rollovers track the existing provisions for disaster distribution 3 year rollovers. Very complex and filing intensive.