There is indeed very little information about this online.
A question asked prior to 2003 on the site 'www.h2.dion.ne.jp' (no longer online):
Q: Do shinkansen trains have power outlet sockets for running laptop
A: Generally, no, although the latest 700 series trains
running on JR West Hikari Rail Star services do have power outlet
Wikipedia confirms that the most 700 series models have power outlets for passengers.
- Hikari 546 is a N700 which have power outlets.
- Hikari 470 is a 700 which most likely have power outlets.
- Max Toki 329 seems to be an E4 series which is not likely to have
Only the N700 trains between Tokyo and Osaka have Wifi, and you still have to pay for it before you board the train using one of the Japanese carriers like Wi2 or Hotspot