1, Apple hires Clojure Devs. Netflix uses Clojure as well. I believe Amazon may in places. There are several other corporate 500 companies that use it in a vast minority of their projects. I asked one dev at Clojure Conj "how many developers do you work with? 100.. How many use Clojure? "No, there are 100 on the Clojure team, we have 1700 JVM developers." Typically these jobs are listed as Experience with one of Clojure/Kotlin/Scala..
2, In all of the negotiations I have had for Clojure jobs, I was offered both routes. The W2 route is often through a staffing company, or a 1099 route on your own. The compensation is pretty much a wash either route. (1099 pays more to compensate for lack of benefits). I am sure there are companies that do direct hire as well.
3, Yes, there are few developers competing for more than one would think number of jobs. It isn't difficult to train up developers to code Clojure, but it is a bit harder to find developers who intuitively architect in the Clojure way. Those guys are a pretty hot commodity.
4, Clojure devs also tend to be extremely experienced. That would mean a high salary no matter tha language.
There are a substantial number of Clojure unicorn companies. Examples are NuBank, Reify health, AppsFlyer, TaxBit, Amperity. Most of these are still under the radar in that most people have never heard of them. There are probably a lot more that haven't hit the Billion dollar mark but still have significant staffing.