Travel from Toyko to Kyoto and Kyoto to Toyko and other questions

Hi there,

I will be travelling in Golden Week from London to Toyko Haneda Airport.

One of my day trips is the following: How much would it be to buy single tickets from Toyko to Kyoto and back on the shinkansen- bullet train? Is it worth it?

It will be my first time in Japan, so I am a bit confused.

With the JR Pass for 7 days at the moment it is 332 euros per person., will this include these destinations there and back?

It there another alternative?

Also, I see that to reserve seats with the JR Pass it is up to 2 to 5 days before I travel. Please can you clarify the above.

Thanks.

Natalie