Welcome to Orchid Talk. While I'm not the expert that many others here are I can reliably say that the keiki in the first photo is mature enough to be cut off and planted in it's own pot. I would trim the spike back to near the base of the mother plant. Both plants should thrive and the parent plant will probably start to grow again since it doesn't have to put it's energy into nurturing it's offspring.
As for the Dendrobium kingianum, well they are keiki factories! Your photo looks like a keiki. These dens are notorious for throwing keiki's, expect many more. My Dendrobium kingianum last bloomed in the Spring if that helps you any.