Here are the steps for renaming a project.
there is a nice python script from @bobc but it has not been completed for hierarchy projects
BTW @HiGreg is it intentional that this topic is @lounge?
About the lounge category
A category exclusive to members with trust level 3 and higher.
Here are the relevant wishlist items:
https://bugs.launchpad.net/kicad/+bug/594051 (active; add a vote here)
https://bugs.launchpad.net/kicad/+bug/1764088 (marked as duplicate)
There is hope it will be added before 6.0 release. Until that, use the help given in the posts above.
I don’t see why not. Only file formats are sacred during a release lifecycle. Obviously V5.0.0 has to be released before it could be looked at.
UPDATE: Save Project As feature has been added to 5.99 (developement version leading to 6.0). It will not be added to 5.1.