[Black Tiger]

You can mod it in the import part, when you import a file, you can give a name in the "author" field next to filename.
Also when you login to the download section you can edit all descriptions if you have give yourselve rights to do that in your usergroup.

If your users can't upload more then 2 mb, you have to contact your hoster or have root acces to the server. Such things are setup in php.ini and mostly also in httpd.conf (apache webserver configuration).