I always assumed his dimensional phasing was a mangekyo power: both where he partially phases out and where he pulls someone into another dimension with him.
Seems an excellent match to Kakashi's portable-blackhole.
I get the impression that Izanami is just one of many Uchiha abilities that are forbidden because they destroy the eye in the process: this one is an ultimate genjutsu. Tsukiyomi lasts for a very short time but seems like days to the victim. I don't think it is limited to a second, though.