Tokyo to Enoura Art Foundation

Hi! Starting out in Tokyo (Shinjuku area) what is the best transit to get to and from Enoura Art Foundation in Odawara. I'm not planning on getting the JR Pass so no Shinkansen recommendations please. So far I'm coming up on: taking the RomanceCar from Shinjuku Station alight at Odawara Station and take the JR Tokaido to Nebukawa station. Then take the shuttle to Enoura Art Foundation from Nebukawa Station.

But there are some clarifications on this:
- does the Pasmo work to take the JR Tokaido to and from Nebukawa?
- do I have to prebook the Romance Car tickets? How far advance should that be done? and do I prebook the to and from tickets at the same time?

Are there other transit options? Trying to find the cheapest and most reasonable option out there and would love to understand the other options.

Also follow up: I noticed that the JR Tokaido line also has Enoshima and Kanagawa area on it's line. Would it be possible to stop by this area on the way back to Tokyo? and still take the JR Tokaido on the way back to Shinjuku?

As I finish up this post, I'm not sure if I totally make sense, but I hope someone can help! Thank you in advance!

Starting out in Tokyo (Shinjuku area) what is the best transit to get to and from Enoura Art Foundation in Odawara.

Here are your options:

The cheapest is to take Odakyu (not the Romance Car, but regular trains) from Shinjuku to Odawara and then take the JR Tokaido Line to Nebukawa (110 minutes, 1100 yen).

Fast and relatively reasonably priced is the option that you pointed out (90 minutes, 2100 yen)

The fastest is to take the Yamanote Line to Shinagawa, then the shinkansen to Odawara and then the JR Tokaido Line to Nebukawa (75 minutes, around 3500 yen).

And finally, you could take the JR Shonan-Shinjuku and Tokaido Lines from Shinjuku to Nebukawa with one transfer somewhere along the way (90-110 yen, 1,690 yen).

- does the Pasmo work to take the JR Tokaido to and from Nebukawa?

Yes.

do I have to prebook the Romance Car tickets?

No, you can buy them at the station on the day. On busy days, they may be booked out.

I noticed that the JR Tokaido line also has Enoshima and Kanagawa area on it's line. Would it be possible to stop by this area on the way back to Tokyo? and still take the JR Tokaido on the way back to Shinjuku?

Yes, the fare increases a little, though.