For changing the photo size see on the top left within the frame.
For downloading click on a picture, then you'll get on the Flickr-page,
and there's a "see all sizes"-button where you can choose the size.
"Posters"-Album on Flickr: http://www.flickr.com/photos/-raygee-/sets/72157626278909671/
Or as a Slideshow: http://www.flickr.com/photos/-raygee-/sets/72157626278909671/show/