Question...

Can I follow the gallery of a certain Celebrity? I'm always looking for new pictures of my favourite Stars...

As far as I know, there is no "follow" for Celebrity pages, like we can "follow" another user in order to get notifications of their Listal activity, new images posted to the site, and so on. By the way, that would be a cool new feature: I suggested something like that in Suggestions.

However, Listal does have "feed" pages for People updates too.
For instance
www.listal.com/sarah-michelle-gellar/feed

p.s. You might want to use a third party tool to subscribe to such feeds.
I am trying the Feedly add-on in Chrome, but there are others.