Directory structure - how do I upload it as-is to an artifactory?
This can be done through the Jrog CLI. The CLI has a recursive option that looks like it will do what you hope.
jfrog rt upload --recursive artifactory-mirror/* artifact-repo/dir-struct/

The CLI also has some performance improvements for uploads that doing it through curl or a browser don't seem to get. Also, scriptable!
To include full directory structure you will want to use the flag --flat=false
jfrog rt upload --flat=false --recursive artifactory-mirror/* artifact-repo