Hakone

If I want to do a half-day tour from Tokyo to Hakone, using the proposed Hakone Round trip course (not the whole thing) only :

Hakone to Gora
Gora to Sounzan
Sounzan to Togendai (ropeway)

You think it is possible?

Are the connections from bullet train to Hakone to each oftransfers easy to find or need to walk?

Worth to buy the Hakone fare if I only want to do part of it?

What activities are good to do? Hope to see volcanic activities, possible?

Hakone to Gora
Gora to Sounzan
Sounzan to Togendai (ropeway)

Gora, Sounzan and Togendai are all located in Hakone! Do you mean Yumoto when refering to Hakone? I will assume so.

Yes, the above itinerary can easily be done in half a day. Without stops along the way, it barely takes two hours.

Are the connections from bullet train to Hakone to each oftransfers easy to find or need to walk?

Yes, they are easy to find, within the same station building with many bilingual signs. It takes about a 2-3 minute walk from platform to platform, not including time to buy tickets.

Worth to buy the Hakone fare if I only want to do part of it?

Do you mean the Hakone Free Pass? Single tickets from Odawara to Togendai will come cheaper than a Hakone Free Pass. What transportation will you take from Togendai?

What activities are good to do? Hope to see volcanic activities, possible?

Then you should make a stop at Owakudani, where you can see some smoke and hot water pools and smell some sulfurous gases.

Thanks Uji. If I stay in Shinagawa Prince Hotel, I could also take the bullet train from there to Odawara for Hakone, correct? Not worth to buy Japan Rail Pas if I am in Japan for 3 days, correct?

Do you know if I am going to Disneyland, what type of ticket should I buy if I have the following itineary:

Sat evening arriving near Disney hotel, departing Monday noon?

Thanks Uji. If I stay in Shinagawa Prince Hotel, I could also take the bullet train from there to Odawara for Hakone, correct? Not worth to buy Japan Rail Pas if I am in Japan for 3 days, correct?

Do you know if I am going to Disneyland, what type of ticket should I buy if I have the following itineary:

Sat evening arriving near Disney hotel, departing Monday noon?

Yes you can take the Shinkansen (bullet train) from Shinagawa Station to Odawara Station.
However note: Not all Shinkansen stop at Shinagawa station or Odawara Station.

Also note that you will be it will be a bit expensive to ride the Shinkansen back and forth, if you were spending that much you might want to consider alternate means of transportation:
http://www.japan-guide.com/e/e5206.html

But if you got the budget, certainly go for the Shinkansen for speed.