Kyoto-Hiroshima-Myajima

Greetings, I would like some help in figuring out time table to see if I have enough time to visit these cities.

As an example how long will it take between Kyoto and Myajama?

as an exemple I will leave Tokyo on the afternoon of september 30th to spend 2 nights 3 days in Kyoto. I would like to go to hiroshima and Myajama and be back in tokyo on October 7th. Is the JR Pass 1st class good on the Shinkasen Blue line?

I am having difficulties with the time table to figure out how much time let's say between Kyoto and Myajama, and then How much time I need to return from Myajama to Tokyo to be there on the 7th?

one last question, as the first class must be quite confortable, I must be able to travel night to maximise my time, ex leaving at 11pm and arriving in Tokyo at 6 or 7 am??