Does this part of the user agreement:

By providing any content to this web site:
(a) you agree to grant the site editor a worldwide, royalty-free, perpetual, non-exclusive right and license (including any moral, intellectual property or other necessary rights.) to use, display, reproduce, modify, adapt, publish, distribute, perform, promote, archive, translate, and to create derivative works and compilations, in whole or in part. Such license will apply with respect to any form, media, technology already known or developed subsequently;
(b) you warrant and represent that you have all legal, moral, and other rights that may be necessary to grant us the license specified in this section 7;
(c) you acknowledge and agree that the site editor shall have the right (but not obligation), at the site editor's entire discretion, to refuse to publish, or to remove, or to block access to any content you provide, at any time and for any reason, with or without notice.

Apply to already submitted challenges before the user agreement was made public to the site? Or after this was published it doesn't clearly state.

IANAL but it does state:

"Such license will apply with respect to any form, media, technology already known or developed subsequently;"

So I guess it does mean stuff already submitted. Of course I'm sure the opportunity is there to have it removed if ya don't agree

This agreement is just for new challenges. If the owner tells me he doesn't want it that way I can also upload it like Phas one's (Hash me...)
Then I am going to put your name and a copyright sign on the button of the challenge page.

ok that is good to know tbs