Redirect authors from upload.php url to Home page in Multisite

If I understand you, he hook you want (WordPress 3.5.1) is load-upload.php. Proof of concept: function t_wpse_94284() { wp_redirect(home_url()); exit; } add_action(‘load-upload.php’,’t_wpse_94284′); That hook should fire only on /wp-admin/upload.php and, though I haven’t tested it, I think that your function should work just fine as it is.

Using common slider in all sites

Do all your sub-sites use the same theme? If they do, then the most light-weight solution would be for you to hard-code the slider in your template file. This will give you the flexibility of doing whatever you want with your slides and the script you’re going to use, but at the same time it … Read more