Welcome back, Moldiver. Yes, you're on the right track...you do indeed need separate MIDI tracks for each MIDI channel you want to drive within Kontakt. That's because each MIDI track is normally assigned
1 MIDI channel. So if you want 16 instruments in a single instance of Kontakt, that'll require 16 MIDI tracks driving each of the 16 instruments, each of which is assigned a different MIDI channel within Kontakt.
An instrument track is really just a MIDI/audio pair, and it's strictly for convenience. There is no technical advantage to an instrument track over just using one MIDI track and one audio track, which is what most of us Kontakt users do.
Personally, I never use instrument tracks. When I insert a Kontakt instance, I select the "MIDI Source" and "First Synth Audio Output" options in the Insert Soft Synth dialog as a convenience. I then manually add additional MIDI tracks as needed (and possibly additional audio tracks as well, if I'm not doing all the mixing within Kontakt's own mixer).
For example, if I've got, say, strings consisting of 1st violins, 2nd violins, violas, cellos and basses (5 separate instruments), I'll have
at least 5 MIDI tracks (more if I want to place articulation keyswitches in their own tracks). The number of
audio tracks will depend on whether I want to mix them all within Kontakt or not. In this example, I'd normally use just the first of Kontakt's audio outputs and one corresponding audio track in SONAR, because it's rare that I'll need to effect each string section independently so they can all be mixed within Kontakt.