Is the 7 day regional pass worth it with the below itinerary

Hello, my husband and 2 kids (under 12) are visiting Japan in 3 weeks. We will be in Tokyo for 4 nights, Kyoto for 4 nights and back in Tokyo for 1 more night before heading to the airport. While in Kyoto we would like to visit Osaka and Nara as well. Do I save money by using the pass from Tokyo to/from Kyoto and to and from both Nara and Osaka while in Kyoto. Is the regional pass for the high speed trains and are you able to reserve seats ahead of time with this pass?

Thanks for your help,
Pam