John
Be sure that you have all audio outputs checked in the properties dialog when you load Kontakt. The other thing I would advise is create a mixer within Kontakt that is set the way you want and save it to be recalled when you start Kontakt. Plus Kontakt comes in 3 output versions 8 16 and 32. You may need to edit its friendly name to show which is which.
You've nailed it here.
The only thing I'd add is *I think* the only one worth working with is the 64 out version (32 stereo)
so I disabled the other 2 in Sonar.
Also, since Kontakt can only do 16 midi channels as a vsti - - -
I built a 16 stereo pairs st.1 through st.16 mixer in Kontakt and set it to be the default every time Kontakt loads and everything has been really easy since then.
Finally, I create templates in Sonar.
1) Project template that is called Kontakt 16
2) 5 track templates K1, K2, K3, K4, K5 so I can easily add an other instace of Kontakt and have the bus routing correct for each additional instance.
My project and track templates have 16 midi channels and 16 stereo audio channels all correctly assigned to that specific instance of Kontakt, all in folders named like "K5 1 Midi" / "K5 1 Audio" so all I need to do is either load a Kontakt multi that has the audio outs for each instrument already assigned, or load instruments one at a time and change the audio out for each instrument.
An other helpful thing I discovered is that we can highlight the title of a Kontakt Instrument in Kontakt,
Hit CTRL+C to copy the name, and then CTRL+V to paste the name into the midi and audio track that instrument uses.