How did obito use Izanagi with one eye?

Obito was forced to use Izunagi because he knew there was no other way around it. Obito defeated Konan shortly after. When Obito uses izanagi, he would normally go to the wall of Sharingan’s he had and replace that eye with another Sharingan but instead he replaced it with the Rinnegan.

Did obito lose his eye when he used Izanagi?

He did not use his original right eye for the Izanagi, but the left eye, which can be seen “losing its light” (closing) as he is talking to Konan. See images below (taken from Chapter 510).

How did danzo use Izanagi?

Since Danzo had Senju DNA in his right arm, he was able to extend Izanagi for each eye up to a minute. Danzō had some of Hashirama Senju’s DNA transplanted into his arm, which extended the time span of each Sharingan’s Izanagi to a minute.

What Sharingan did Tobi/Obito use for Izanagi?

We know, as mentioned above, that Tobi/Obito didn’t use his original sharingan for Izanagi but instead he used the Sharingan of the left eye. This may have been the Sharingan of Shisui. I conclude this, because after Saskuke defeted Danzo, Tobi used Kamui and kept Danzo’s body with him, saying he has something to do with.

Why does Kakashi still have a Rinnegan with Izanagi’s Sharingan?

As per my understanding, Izanagi permanently blinds the Sharingan’s vision once used. Tobi (Obito) donated one eye to Kakashi, and used Izanagi with the other eye to escape from Konan’s paper bombs. This means he should only have a Rinnegan now, but why does he still have a Sharingan with Kamui ability? Note: I do not read manga.

Will Izanagi’s eyes ever open again?

Yes those eyes were getting blinded, but not permanently. If you posses the senju DNA you would be able to reuse Izanagi within a day time, i.e. the sharingan eyes will open again in a day time. I am not confusing with the koto amatsukami. I guess that partly answers your question.

What is Izanagi’s ability?

Izanagi is an ability that will blind the caster. However, those who posses the senju DNA can cast is again and again and again. Source: When danzo was fighting sasuke, he used Izanagi. The eyes in his arm were shutting down one by one. Yes those eyes were getting blinded, but not permanently.