Hi,
1. You know, I haven’t used the gallery feature. But I think it’s a wordpress feature rather than a graphene feature. I believe the page in that link is just to show how it looks when creating a gallery. While you are on a page in the editor, click the button to insert an image. Then, if you scroll toward the bottom of that popup screen, you should see options for a “gallery” page.
2. Are you wanting these images aligned to the left? Why not just define it in the editor when you insert the image?