How do i get the node id using menu_hook
Although you pass a node id into the url, it get's converted to a fully loaded node by the time your callback function is called. You could read up on it on the documentation page for hook_menu, under section Auto-Loader Wildcards.

In node.module you will see this menu item for node edit:

$items['node/%node/edit']


Now, the path you are trying to register already exists in the node module, so that is where the WSOD comes from. You need to do a hook_menu_alter on it, or perhaps hook_form_alter if all you want to do is alter the node edit form.