Not exactly sure what you mean here. You can create “new” vaults in any folder. So, in fact, you can export your Roam database, duplicate it a few times, and then try different things with each to see what you like. A change to one vault on one folder certainly won’t influence the content or settings of another vault on another folder.
Edit: hit cmd+enter too soon. Sorry.
Not via any core feature. You could, however, embed a photo in a note and add your metadata to it there, then embed that “photo note” elsewhere.