Adding images to a gallery
Any project has an gallery which is provided with images from post attachments.
This means that if you attach an image to a post, that image will apear in the project gallery.
For example when you upload an image into a project that image gets also attached to the project.
Ordering images through gallery
You can also order images by clicking on Add Media button, then on Media Library tab and select "Uploaded to this post". Now you will see only the images attached to the current post and surprise : You can drag and drop images around. That is the order from the project gallery too.
Removing images from a gallery
Unfortunately wordpress doesn't have a "Detach" button in the media uploader, but you can always use a plugin like this http://wordpress.org/plugins/unattach or http://wordpress.org/plugins/file-un-attach to remove an image from a gallery.
Have fun with your project's presentation!