I used Gallery 2 a couple of years ago, and I notice that google cache the images and gallery. Is it possible to stop them from doing this, maybe some code in the page? If an album is not published, can Google cache those also?

There is an example robots file in the root folder of the installation. Maybe you can configure this to exclude Google from caching things. Otherwise someone knowledgable in how Google works will have to provide you the answer.

Certainly Google can cache unpublished albums if it somehow finds them, but they would not normally be seen by webbots.

create a google Webmaster account and register your url, here you can opt out of having your images loaded into google image search...

http://www.google.com/webmasters/tools/