Selecting all photos in photo booth with a single gesture
EDIT: (Originally I had described a way to select multiple photos via the "Photos" app, and I didn't realize you could do that directly within Photo Booth.)

In short, no, you're not missing a secret gesture -- that's currently the only way to do it.

And unfortunately, I do not believe there is a way to create a new photo album on the iPad itself -- you'll have to do that on your computer and sync with iTunes to see the changes.