Tokyo - Nozawa - Tokyo - Osaka - Tokyo

Hi there, I am trying to work out if the following if it makes sense to purchase a JR pass for my upcoming holiday. If it is better to buy individual passes or train tickets, how do I do that and can I pre-purchase them here on this website?

Day 1 - Airport Limousine Bus
Day 2 - Omiya Saitama to Iiyama Station
Day 3 & 4 - Ski Resort
Day 5 - Iiyama Station to Shinagawa Station
Day 6 - Shinagawa Station to Fukushima Station (Osaka)
Day 7 - Fukushima Station to Nara Station (Round Trip)
Day 8 - Fukushima Station to Kobe (Round Trip)
Day 9 - Fukushima Station to Kyoto (Round Trip)
Day 10 - Fukushima Station to Universal City / Universal Studios Japan (Round Trip)
Day 11 - Fukushima Station to Shinjuku Station (Tokyo)
Day 12 & 13 - Sightseeing within Tokyo / Shinjuku
Day 14 - Hotel shuttle bus to DisneySea
Day 15 - Hotel shuttle bus to DisneyLand
Day 16 - Sightseeing within Tokyo / Shinjuku, Airport limousine bus

We are trying to work out if it is worth it to purchase a JR pass, and if so, should we get a 14 day pass or is a 7 day pass enough? Thank you!!!