Please help to use the Japan Rail Pass

My husband and will be in Japan from March 28 to April15 .
This is our planned route :
1/ Tokyo ( from March 28 to Arpil 3)
2/Yokohama ( stay here for 1 night - Arpil 4)
3/Mount Fuji ( stay at Hyatt Hakone for 2 nights - April 5 and April 6)
4/Osaka ( stay at the hotel in Osaka for 3 nights - April 7,8,9 )
5/Hiroshima (stay at hotel for 2 nights _ April 10 , 11 )
6/Kyoto ( stay 2 nights in kyoto hotel - April 12 ,13)
7/ Osaka ( stay 1 night in Osaka _ April 14) ...
and We will check out of hotel in April the 15 , go from KIX aiport to SEOUL .

We will be at Narita Airport in March 28 .......Please help , at the time We stay in Tokyo , do we really need the JRPass ? Can I buy the metro pass around Tokyo ? And from April 2 - to April15 buy and use the JR Pass for 14days ?
Thanks .
M.Vu