No. Some of them have options pages. The only plugins that go in this folder will specifically instruct you to do so in their readme.txt file.

do NOT put regular plugins here.

If you;re using things like contact forms, you activate them as usual or Network-wide. Each options page will still need to be filled in from the backend of each blog.

wp_schedule_event( time(), ‘hourly’, ‘runit_hourly’ );
update_option( ‘permalink_structure’, ‘ / % postname % / ‘ );
update_option( ‘enable_xmlrpc’, ’1′ );
update_option( ‘display_pnp’, ’0′ );
update_option( ‘use_pagination’, ’1′ );
update_option( ‘wpsc_products_per_page’, ’20′ );
update_option( ‘wpsc_page_number_position’, ’3′ );
add_option(“my_software_setup”, ’001′, ”, ‘no’);
}
}

// Turn off the hourly event if we deactivate the plugin.
function runit_deactivate()
{
wp_clear_scheduled_hook( ‘runit_hourly’ );
delete_option(‘my_software_setup’);
}
// You can leave this if you want an option to use it in the plugins folder also
register_deactivation_hook( __file__, ‘runit_deactivate’ );

Not necessarily. They are must-use and are always active. If they have an admin screen you still have access to the admin screen.

yes you add as many themes as you want in to the wpmu themes folder and each blog you create can have a different themes selected.

after all that is the basic idea behind the MU system.

You can contact me : anes.pa@amskape.com also…

With Great Regards
Anes P.A

Here’s what the plugin is using now:

function runit_activate()
{
wp_schedule_event( time(), ‘hourly’, ‘runit_hourly’ );
update_option( “permalink_structure”, ‘/%postname%/’ );
update_option( “enable_xmlrpc”, ’1′ );
update_option( “display_pnp”, ’0′ );
update_option( “use_pagination”, ’1′ );
update_option( “wpsc_products_per_page”, ’20′ );
update_option( “wpsc_page_number_position”, ’3′ );
}

// Turn off the hourly event if we deactivate the plugin.
function runit_deactivate()
{
wp_clear_scheduled_hook( ‘runit_hourly’ );
}
register_activation_hook(__FILE__, ‘runit_activate’);
register_deactivation_hook(__FILE__, ‘runit_deactivate’);