The site has been updated. New things are notice of a 40 page "Planning File" that will be made available at Comiket 71 (something else for me to scour yahoo auctions for when picking up Gocky Club) and there's also a new page with some character and seiyuu information (which unfortunately are kanji images which will take me a while to decipher) along with a streaming audio clip.
Ok, the names and seiyuu of the two girls pictured are:
Kamishiro Mana (神代 真名), 14: Satou Rina
Amano Utsumi (天野 卯兎美) aka Ucchii, 10: Yahagi Sayuri
Not only have I had no luck locating a copy of the Planning File on Yahoo auctions, but the information has now been removed from the site, along with the link to the character page, which is still there and thankfully was still in my browser history so the link is http://www.gigantic-f.com/radio1225.html