Hello Kitty Shinkansen - non-reserved seating and reserved seating

Hi Daniel

I have two questions:

1. I have purchased a JR-West Pass - Kansai Hiroshima Area Pass. I know that I have to exchange the Order for actual passes, that I will do at KIX upon arrival on Day 1. Then on Day 2, we would like to take the Hello Kitty Shinkansen Kodama No. 849 from Shin-Osaka to Hiroshima. Can we just show up at Shin-Osaka station with our luggage and board the train for non-reserved seating? What if the train is full, can we still board this Hello Kitty Shinkansen?

2. As we do not have actual passes yet, can we make reserved seating online for the Hello Kitty Shinkansen? I read that reserved seating must be made 1 month in advance. If we cannot make reserved seating without actual passes, can we make it on the day of travel itself, i.e. on Day 2 in the morning? If yes, how early should we do it considering the Kodama No. 849 leaves Shin-Osaka at 11.37 am?

Thanks