1) You will not be eligible for any Sapphire card until 48 months after the previous bonus, that would be 9.16.2023. There have been a few reports of applications approved 48 months after the threshold spend was completed to earn the previous bonus. You may be able to reconstruct that date by looking at your 2019 statements, but for planning purposes I would assume that 9.17.2023 will be the application date.
2) Chase always bills renewal fees on the 1st day of a month. If it was not billed on 8.1.2023 it should be 9.1.2023. Look at your most recent paper/PDF statement for a notification of the renewal billing date.
3) You will not be eligible to open a Sapphire Reserve card if you hold any other Sapphire card. If your renewal fee is billed on 9.1.2023, downgrade to any Freedom card around 9.10.2023. This will allow the change to be reflected in Chase's system when you apply for Reserve on 9.17.2023.