Kimi, on the upload page of your gallery beside the edit button you have an Image order button, click on it then it will take you to the next page where you can select the Gallery Image, which will show on the page before you open your gallery. I hope This helps, I haven't started my second gallery yet, so I don't know the answer to that one.
Glad you got it all figured out. Even though you numbered them - select your gallery favorite so that even if you add pictures it will still be the front for your gallery.