Our apps are in 2.2 version. Our question is: would we be able to use the old tooling and edit our apps as is, without upgrading to 2.3? Is there a deadline for upgrading to 2.3?
No, the apps in platform version 2.2 must be updated to platform version 2.3 to publish a new version.
All the apps in platform version 2.2 that are already published will continue to work.