Hi Randy
Cubase is pretty much the reference VST host - Steinberg created and defined the standard, so if a VST doesn't work in Cubase there's usually something wrong with the VST. Cubase is actually a very good DAW, lots of professionals use it as their main studio tool. The new Note Expression feature plays nicely with the Eigenharps in editing performance data. Years ago I used it for a while as my main sequencing software and found it very usable.
Getting MIDI and Audio in and out of it from EigenD is a platform dependent issue and is, as far as I'm aware, no different from Reason. Are you planning on running it on MAC or PC?
John