Is it worth it to buy a JRP

We will be arriving in Tokyo on 3rd Sept, our plan is to go to Odawara (then to Hakone) on the 4th Sept for 2 nights, then on the 6th to Kyoto and then on the 8th back to Tokyo for our last few days (so we won't need a JRP)

We were planning on getting a JRP so we could get the bullet trains to all destinations (we will also be traveling with our 2 year old, can I confirm he is free)

Is it worth it cost wise v's time it would take on normal trains?

And will the JRP cover us for all of these stops

Thanks
D