You can Export/Import projects. Might not be any practical difference between Copy/Paste, though. (I don't know enough about what happens under the hood.)
You'll have to change the Cache for each project manually.
The Cache location is an absolute path, so if you want to change with each project, you'll have to set it manually every time. Personally, I find that cumbersome and find the best approach is to have a dedicated Gallery/Cache/Optimized Media/Proxy drive for all projects.