Japan trip

Sir,
We are 4 adults traveling to japan in April 2018. Our itenerary is as follows.
7th April reach Narita Airport 9.00 AM shift to Osaka from Airport
8th Visit Hiroshima & Miyazami
9th & 10th See Osaka & Kyoto
11th transfer to Tokyo . Evening Tokyo visit
12th Mount Fuzi
13,14 & 15 Around Tokyo
16th April departure from Narita Airtport 11 AM.
Sir, my questions are as follows
1. If I purchase 7 day JR Pass in advance, Will it be possible to exchange the voucher & get the pass
at Narita Airport so that I will be able to use it instantly in Narita express. 2. As my 7 day pass will expire on 13th April midnight & still I have 2 days 14th & 15th & on 16th have
to go to Narita. My question is whether I should purchase 14 day JR pass or 7 day pass & remaining days by other tickets. Also suggest me in 2nd case what ticket I should take for remaining 3 days . Thanks.
Dr. Sunil Goyal. India