I believe the shared folders are available via UNC. The permissions can easily be modified.
I clearly understand why you went whith flickr. My DSL line offers only 2500/500kbs. 500kbs doesn't feel like broadband when I want to download pictures etc. from mye WHS when out traveling. With regards to space, mye WHS got 1TB of capacity, and right now it's 25% full. I have a lot of space available, and my wife and myself have both computers (Windows Live Photogallery) mapped to the shared photos folder. This is great for adding tags, editing photos etc. Windows Live Photogallery now also supports upload to flickr with just a simple click.
WHS doesn't offer any Gallery functionality out-of-the-box. Neither does it offer any website creation tools. Andrew Grant has written a tool for creating a simple photogallery and for creating a simple web-page. You can find it here: http://forum.wegotserved.co.uk/index.php?autocom=downloads&showfile=63
I heard about dotnetnuke, and sicne it works fine with IIS I wanted to give it a try. With dotnetnuke I will have a really good website solution, and also the possiblity to extend the funcitonality by adding modules. Since I want to store all my photos in the "Shared photos folder" I would like to have a solution where I easily can view our photos externally.
If you manage to write a gallery module that offers this functionality, I would happily test it for you. If it becomes a success I would encourage you to have "WeGotServed" to review it. I would also be happy to offer you a donation if it works well!
Kind regards,
Tom-Roger