susanoo need 2 ms as TRIGGER. once you've unlocked it, he can summon or use susanoo anytime. example, itachi was already blind vs sasuke when he used susanoo.
Yeah without MS, you wouldn't be able to use kamui. It's common sense that the base sharingan has no "special" abilities like kamui, yet Kakashi doesn't even have a sharingan, let alone MS.:hyper: