Seat Diagram of VSE (pdf file)

If you have a seat 4A or 4D in Car No. 1 then you are in one of 16 front view seats. Obviously seat 1A, 1B, 1C, and 1D are the front seat which are premium seat which sell out fast.

As to if you should go with Romancecar or Shinkansen? Well, I will be biased because I am a train geek. You will ride on Shinkansen when you are traveling from Hakone to Kyoto anyway, so why not ride on something different from Shinjuku to Hakone? Sure, since you do have JR Pass taking Shinkansen from Tokyo to Odawara will save some money compare with taking Romancecar…, but as I said I am a train geek so my opinion maybe biased.

As which is simpler…, where in Tokyo are you staying? Romancecar will take you directly to Hakone-yumoto from Shinjuku. Taking Shinkansen you do need to transfer at Odawara. Romancecar is more popular than Shinkansen for trip to Hakone, because local Japanese residents do not have such thing as JR Pass. Fare on Odakyu’s Romancecar is cheaper than JR Shinkansen:

Romancecar: Shinjuku-Hakoneyumoto JPY 2020
Shinkansen: Tokyo-Odawara then to Hakoneyumoto JPY 3770

This is the reason most local Japanese in Tokyo heading to Hakone take Romancecar. In your case I think it is your call…