Yes, it is in progress, but slow. Here is the forum thread on it:
Supercharger-Burley Heyburn Idaho
Tesla had contacted the owner of that shopping center in the fall of 2018 to start arranging things there in Heyburn. The last status update we had there was on July 20. Since there are several stores there that share the parking lot, they all need to approve it, and the Ross store still hadn't signed off yet.
Depends on the time of year. Plugshare shows that there is an RV park in Snowville, UT that is open from March 1 to November 1, so when it's not winter, there is an accessible place in the middle of the route.
Yes, that one opened up within the past few months, I think. It is interesting how EA is getting a lot of this I-84 corridor covered out in the northwest. I was just talking with a coworker friend out here in Boise about electric vehicles he is considering. They go to Seattle frequently, and I found that EA has the whole route from Boise to Seattle covered with their sites, so it's not just Tesla that can do that now.
That is a route I've been pondering and half planning a few times and have a plan worked out of how I would get down to Las Vegas. From Twin Falls, I would go down to West Wendover to charge up, and then it goes southwest on alt-93 to rejoin main highway 93 toward Ely and then down toward Panaca. That would be the long segment, from West Wendover to Panaca. There is a CHAdeMO in Panaca, and then it's easy from there to Las Vegas.