SO, that does not make it correct. Try it. Any folder you create in the gallery and any images placed in that folder will be in the pictures folder (assuming that is your default images folder).
Do not give me grief, I do not need it. Got it...
Online images are shared on the services only, they have to be copied from your drive to that service. The files can be accessed with a web browser or other app to copy them back to your drive, assuming you still have the password. Meaning the files do not have to be copied to a flash drive at all (unless you want to)
The editing done in the gallery works the same as it does in lightroom, it puts the edits in the metadata, allowing you the chance revert back to the original. In other words it does not affect the pixels making it non-destructive.
You can select any image in the gallery, right click on it and choose to edit in photoshop. Just be aware photoshop can do destructive edits (change the pixels).
The difference between gallery and lightroom is gallery is using the file directory, whereas lightroom uses a database, (just an FYI)