Yesterday it fine in the city. Apparently it is difficult in the surrounding areas

Don't bother with a tour. It's simple to get around on foot and you can get headphones with English translation. Inexpensive and intensely moving experience. The City of Hiroshima is beautiful and very peaceful with wide boulevards

Hiroshima has plenty of places for sight seeing. Other than the Atomic Dome and Park, there are other places you can go. Their shopping district is good. I personally like it as it it's sheltered and you can walk and window shop the long stretch. Since you have JR pass, take the express train to miyajima and then transfer to the ferry to go to miyajima island to visit the shrine and the floating Torii Gate. You can also see many deeds too. If you have time climb up Mount Misen either by cable car or trek up. The view at the top is amazing. Then on the way back, u can try the grilled oyster and fried curry donuts. Heavenly.

It is in an open park so it is always open. The whole park has various places within it, one site being the Atomic Bomb some. the museums keep open and closing hours. Hope this helps.

Still not done when I was there mid-March of 2016.