Shall i get 7 days or 14 days JR pass?

hello there,

I would appreciated a bit of help. I am arriving to Narita on the 10th of March. While i am in Tokyo I am planning to visit the city and then do some travelling (day trips to Nikko and Kamakura ).

On the 16th of march i am taking the train to Kyoto. Once again while i am in Kyoto i am planning some day trips to Nara and Kiyomizudera Temple. Finally on the 20th of march i am departing from Kansai Airport.

As you can see i will be in Japan for 10 days and it is lots of travelling involved; my questions are:

what type of JR pass shall i buy? Is worth it to buy the 14 days pass or the 7 days pass will do?

What about the daily passes to visit Tokyo and Kyoto central? How they work?

This is my first time travelling to Japan, any comment or suggestions will be more than welcome

Thanks for you help

Nadia