Regional pass without reservation ok?

Hi, need your advice.
I will arrive Kansai Airport 12Jun'19. 5Adults, 2 children (7 &11). My brief itinerary:

13 & 14 Jun : Osaka --> No JR passes needed
15 Jun: Kyoto --> No JR passes needed
16 - 20Jun: Travel day trips (Nara/Kobe/Kinosaki Onsen/Shirahama etc) from Osaka using 5days Kansai Wide Regional pass
21 - 25Jun: Travel furthest to Hiroshima + day trips (Okayama/Himeji/Miyajima etc) from Hiroshima using 5days Kansai-Hiroshima regional pass. 25Jun back to Kansai airport for return home.

Question:
1. I noticed that the Kansai Wide and Kansai-Hiroshima cannot / does not include free Seat reservation. Will this be a big problem for my group of 5?
2. Instead of buying Kansai Wide + Kansai-Hiroshima (total 10days), would it be sufficient to just buy a Sanyo-Sanin Area pass (7days) which includes free seat reservation?

Thank you very much!

Best Regards,
Beny