Many of the ideas/proposals you've listed falls into the category of requiring some sort of powerful tether such as the elevator, launch loop, space tethers, skyhook, and possibly the orbital cable idea. This is currently limited by materials science/our ability to produce the required material in mass quantities.
There are many companies working on stronger tethers (mostly carbon fiber/graphene type stuff). In fact, there's lots of research institutions (such as MIT) working on getting graphene to leave the lab and become industrially produced. This might "accidentally" unlock the technology needed for all these tether-related technologies.
As for the megastructures requiring active supports such as the fountain or the loop, I couldn't find any company or research project that has left the hypothetically-physically-possible-drawing-board phase.
There are a couple thinktank-companies and old space agency plans for orbital rotating stations (or parts of stations), although not usually in the scale of a full blown Bernal sphere. There's lots of discussion and speculation on forums and the consensus seems to be that making a rotating space station today would be feasible--just expensive and counterproductive: The main advantage orbital space currently has over earth is primarily the micro-gravity environment and maybe secondarily as an isolated environment. For a rotating habitat to make sense, it would house scientists and tourists who want to sleep in gravity but work in micro-gravity or preform experiments at lower gravity levels.
The furthest any space-related megastructure has gotten is probably the StarTram concept which proposes a cargo and a human space launch system which uses a really long evacuated tube (130km for cargo, ~1300km for humans). They claim that the technology needed to build it is here today and there have been cost-estimates citing a construction cost of ~15 billion for the cargo version and another ~60 billion for the human version if construction began in 2010. This launch method probably has the most serious artist's impressions out of all the space-megastructures.
If I had to guess the order at which these will be developed (if!) Id wager that we'll see an orbital station with artificial gravity within the next 10-40 years. If the space industry is worth it, I expect a non-rocket space launch system will come after that, probably a tether-based design.