The norwegian CMS eZ Publish (http://www.ez.no) sounds about perfect for you. It can do all the stuff you mentioned and you don't have to touch a single line of code besides the HTML layout.
It shouldn't be too much work to configure, either. Create a datatype called something like "Game Prediction" (or whatever you find suitable) with the attributes required.
Use the "Approve" workflow event to require confirmation by you (or any other administrator/user you want), and exclude a usergroup "Selected writers" to allow users of that group to be able to post predictions without needing confirmation. For more information about the Approve workflow, check out: [ez.no...]
The CMS already has a user registration and you can easily add/remove wanted/unwanted properties from the user class.
All URLS generated by eZ Publish are very search engine friendly.
The complete layout of the page is controlled via templates - and they are extremely configurable/extendable.
Learning to configure and use eZ Publish requires patience. But once it's setup properly you have a rock solid CMS with endless extensibility possibilities.
For more information, check out www.ez.no or the documentation at www.ez.no/doc
EDIT: eZ Publish also supports translations, both for content and layout/static text.