Tokyo, Hakone and Osaka Transportation

Dear All,
Need some help,I intend to visit Hakone in Dec 23th for 3D,2N.My base is from Villa Fontaine Shiodome.
1.Which transportation is the best to reach Odawara between JR Tokaido Shinkansen from Tokyo Station or JR Tokaido main Line from Shimbashi station.
2.Do I need to buy train ticket in advance since Dec 23th is a holiday in Japan?
3.From Odawara to Osaka I will catch Kodoma or Hikari train.Do I need to buy train ticket in advance while I arrive at Odawara on Dec 23th since I will traveling on Dec 25th (christmas and weekend).
Many thanks for your help.

1.
Tokaido Main Line is easier(no transfer), while Shinkansen will be faster and worth the effort if you have JR Pass then.

2.
Doesn't matter. The ticket office is open everyday from 7AM to 10PM.

3.
It's ''recommended'' to reserve your shinkansen seat in advance if you can catch the specific shinkansen, since it gets crowded as new year holiday season approach. But it's not something you ''need to''.

Dear V,
Many thanks for your help,its so clear to me.I don't ???è JR Pass so Tokaido Main Line from Shimbashi station is the best choice for me.
One more inquiry V,Is the ticket counter easy to find in Shimbashi station,since I can't speak and read Japanese.

Thanks,
Elhastuti

so Tokaido Main Line from Shimbashi station is the best choice for me.

If you start the journey from Shimbashi Station, taking the JR Tokaido Main Line from there to Odawara will be your most cost-effective choice.

Is the ticket counter easy to find in Shimbashi station,since I can't speak and read Japanese.

You don't need to go to a ticket counter. Just buy your ticket at a machine, which are easy to find (or use a Suica prepaid card).

Hi Uji,
This Forum always impress me.
Many thanks for your help Uji.

Regards,
Elhastuti