It might be easier if you go to CLI then just type "show | grep -f interface_name or other _object_name_to_be_moved" to find out all dependencies.
But now all interfaces should be in root vdom. So you don't have to move the wan interfaces if you make root vdom as your internet vdom as in the admin guide.
But you should prepare npu_vlink or vdom_link between root and new vdom(s) first, then change existing policies in the root vdom to use the link(s). This is also probably easier if you do with CLI.
Just make sure you have the entire config backup first before start moving/changing things around. Then you can copy&modify&paste at new vdom(s).
PS. When you modify the config to be pasted after copied from the existing config, don't forgot to remove "snmp-index" and "uuid" lines before pasting into a new vdom. Let the 40F decide the reference number/ID when a new object is created.