Yes to pretty much all of the above. It's an extremely terse array programming language in the APL family, but with ASCII primitives and strong distributed programming / IPC support. There are also at least a couple companies that still use K3 (I work at one), and no official support from the author (who went on to make other versions of K that are also awesome but completely different).
IMHO the biggest thing holding K back is lack of a production-ready / batteries included open source implementation. (There are a couple nice open source implementations of K but none of them are as feature complete as this one... Plus this one has at least a start on interoperating with .NET)