WordPress.org

Can you upload photos directly from the post edit page?

No. Upload them to the media library directly; it works better.

Can an image be in more than one gallery?

As of right now, no. If folks feel the need to do this, I can implement that feature. Please note that the images are still available to do any other WordPress stuff (eg. insert into post content), but may only used once within Before/After.

I've set it up this way to avoid confusing multiple images in the admin interface.

How is Before/After styled?

It is not styled in any way. The plugin gives you an admin interface, and the template tags to build any kind of gallery you want. Style it with CSS, or use it in conjunction with a javascript library like jQuery.

To use this plugin you must be familiar with theme files and rudimentary PHP.