Header and Demo site questions...

Hi there,

How do you add a “sticky” header with a top bar to the “dev theme?

Have you tried this?
https://docs.generatepress.com/article/sticky-navigation/

Also, if after importing a demo site I then decide that I wish to change or switch it for another one, what’s the best way to “swap it out”, without leaving a bunch of content and code from the original one?

This should be the best solution:
https://docs.generatepress.com/article/removing-imported-site/