Will be there in a few weeks. Not sure where to stay or what to do except take in the normal things you do when visiting as foriegn country.
We are not upmarket travelers.
We loved Hana Hostel ( it may be called Hana Hotel) .... they had everything we needed and were a very short walk from Hiroshima station.
The hosts were some of the most helpful we had found in Japan. and the common room was always full of friendly people hanging out.
It is also a very family friendly Hostel. about 5 years ago
In terms of the best way to get around, we often used the tourist bus route or the trains. The tourist bus has a special stop at Hiroshima station and the hostel we stayed at gave us lots of information about it. There are two routes (green and orange) for this bus and it stops at all the main sites in Hiroshima city.
If you decide to go to Miyajima Island, which we highly recommend, you will need to catch the train, and then a ferry.
There are also some JR trains, so if you have a JR pass you may want to use those. about 5 years ago