The US never adopted teletext on any significant scale but they had the V chip activated using data on line 21 of the VBI.
No - though a number of US stations ran services in the early 80s. Most used the 525/60 version of WST (i.e. the same system used in the UK modified for NTSC) - and I think TBS in particular ran a service. Zenith made TVs that had decoders, but when they re-engineered to add stereo functionality to their range, the teletext functionality was dropped, as by then it was clear it was going nowhere.
Some other stations in North America used a different system - NABTS (North American Broadcast Text Service) - which I think was originated in Canada and may have been linked to the French Antiope service a bit (France had their own bespoke teletext standard for a number of years before switching to WST).
Subtitles (aka Closed Captions) in North America are delivered using a separate system (much cruder, but also more robust, so it survived VHS recording) and the V-Chip system was integrated into this standard AIUI.
Yes, the service (W)TBS had was called Electra. They pretty much had nothing to do with it though. The service was in fact created by Taft Broadcasting in Cincinnati and broadcast by their flagship station, WKRC-12. It wasn't until 1985 that Electra went national. This was achieved by Satellite Syndicated Systems/Tempo Enterprises, the people in charge of uplinking WTBS to cable companies, putting it in on their end (ergo people in the Atlanta area who got WTBS over the air couldn't use Electra). Tempo also carried Electra and its' sister TEMPO Text (which from what I gather was mainly used for stock quotes and possibly sports stuff) on its' own Tempo Television network, which was mostly aimed at C-band dish owners and ended in 1989 when NBC bought the transponder to launch CNBC.
Aside from that, there were also a duo of services offered via the Discovery Channel: "Infotext", which carried agricultural related info as well as news and sports, and "Datavizion", which was family-oriented and was essentially the Fun & Games section of Ceefax combined with weird news stories and a satellite TV guide.
I've only ever found one or two pics of Electra and none at all of the other services. I have no idea if it's possible to extract pages from tapes of these channels as the Zenith-created teletext decoders (which were only compatible with Zenith TVs) seem to have vanished into the mists of time and Zenith TVs with the decoders built in are rather rare now.