Izanagi and Izanami can not be transferred to another user?
It's an ability that all Mangekyo users can use. It's an ability that you gain if you awaken the Mangekyo. The same as the Sharingan Genjutsu which also is an ability that you get automatically when you awaken the Sharingan.
black zetsu=kaguya will and originator of all tojutsu power
Don't know what this means.
It's not that Obito couldn't use Kamui, but that he didn't even try to. He didn't need to use it and that is why he didn't use it, but Madara did which says a few things about Madara.