OK, well first I'm not sure, if it's in the same position it cranks/stops-cranking/& runs in, How
that works. Does the Ign Sw "feel" normal? That is, does it do the "Spring Back" from the, normal, starting position properly? Can you even go there?
See, if there was
just One position I would think you'd hear the starter running. So, maybe what's happening is that the Run and Start contacts in the switch aren't right (like it was bad) and you're not really aware of the subtle position change? I just can't make sense of it otherwise
How would the starter be disengaging.....
As for the PRNDL, if the pawl in the trans engages (so it's not rolling) and Neutral is in "N" then, I'm not sure how it can be related. What do you mean by a "humming or whining"? Where is That coming from? The Trans? The Dash area? Under the hood?
I'm Sorry I'm having such a problem relating to your troubles, I can't envision any of it!