Shin-Iwakuni Station (Booking Reserved Seats using JR Pass)

Hi ,

1st Question :

I will be travelling to Kansai Airport - Shin Osaka - Shin Iwakuni using JR Pass.

But on the return trip , from Shin Iwakuni where can I book the reserved seat ticket using the JR Pass ? Is there a JR Office in Shin Iwakuni Station ?

2nd Question :

From Shin Iwakuni , we want to go to Shinjuku.
I am planning from Shin Iwakuni - Shin Osaka - Shinagawa - ( Change to take N'EX ) - Shinjuku.

Does the JR Pass cover Narita Express to Shinjuku ?
Where can I book reserved seat of Narita Express.

Many thanks in advanced !