in answer to your questions if you use pro to make it you can still edit it when you stop being pro also yes anything you make in either pro or normal will stay accessible by all ok. i know coz i only go pro when i want to make a pro face.
I guess you watchfaces with Pro options will be still accessible after the downgrade.
During the Montblanc contest, I designed some faces with pro options but I’m a basic creator user.
Now the contest is over, these watchfaces are still accessible and I can modify them but can’t add additional “pro options” anymore.