Upload images to Media Lib or GmediaLib?

General question: I noticed you can import images from the Media Library to the Gmedia Library or just upload to the GMedia library – Is it best to upload directly to Gmedia? What if the image is used in a post but, not in GMedia Gallery or album? Can images be used in WP post if they are in GMedia Libary?

Say I have an hundreds of images currently in WP Media Library – and took the time to add tags & categories to them – can gmedia import the tags & categories, rather than having to RE-add the tags & categories again?

Any input would be helpful – yes brand new to GMedia

Dee