which JR PASS

A 7 day JR Pass would not be cost effective for your itinerary. You'd need to long distance across the country.
You can look up regular rail fares and schedules on Hyperdia.
It's possible you could get some savings from a Kansai Thru Pass although it'd take a pretty good amount of going around to make it worth it. Probably regular fare tickets will serve you just fine. If you can, try to put in at least half a day to see Nara. Along with Kyoto it is a former capital and one of the crown jewels of Japanese culture. The Todaiji Great Buddha is a must-see place and there are many other good places in Nara Park there as well.

Best of luck.

If you are willing to travel a bit more, than some other regional passes might become good money savers. Nearby Osaka is Himeji, which has Japan's finest surviving castle, and it is well worth seeing. A JR Kansai Area Pass or a JR Kansai Wide Area Pass might help you.
In addition, there are other numerous great places you can visit in the area. Okayama is not far and it is famous for its castle, plus Korakuen, one of Japan's Top 3, and also the Handayama Garden. If you'd like to get off the beaten trail for a while, the half day hike up to Konpirasan in Kotohira is stunning. Going to Takamatsu is also nice - it has one of Japan's finest gardens also, called Ritsurin.
Hiroshima also has a number of good places. Miyajima is the most famous, and aside from Hiroshima itself, Onomichi with its temple tour and Kosanji Temple is spectacular. Just beyond Miyajima also lies Iwakuni with its historical bridge and castle on top of the mountain. Taikodani is also a beautiful shrine in Tsuwano, Shimane. Hagi Castle was actually delightful, and the preserved samurai district and Mori related temples a rarity. One of the very best is the Akiyoshi Limestone Cave, a 300 million year old wonder with huge caverns and underground river running through it.

In total, there is a lot more to explore and enjoy.