I've seen it mentioned a few places but couldn't find a summarized answer on which trains have wifi access, how much it costs, and how to get on. Can someone fill me in/confirm?

What: Wifi speeds on the shinkansen go up to 2 Mbps for download?
Where: I have an impression that it is only on the N700 including Hikari and Kodama between Tokyo and Shin-Osaka.
Requirements: A cell phone that can receive txt msgs is required to get the activation code in addition to the wifi device (802.11 b/c enable laptop/smartphone/tablet).
How: You sign up while still at the station by logging into the wifi portal, paying, and receive the activation code via txt. Then you input that using laptop/phone to activate the internet connectivity on that specific device.
How much: Don't recall the cost.

Thanks!