Thanks everyone, lots of good advice, as I expected.
Not sure my question #1 was answered. My fault: my post was too long. Let me rephrase it:
Question #1: If the sub-EGR valve sticks open - either half or full open, stuck - what will happen? Will it affect idle?
Also keep in mind this is a dual-EGR truck - has primary and secondary EGR valves. The manuals say the primary EGR valve operates at "relatively narrow throttle valve openings". Does that include idle?

@geezer, thanks for the advice. I will certainly follow it as far as adjusting fast and warm idle speeds. You confirmed my idea of how the secondary throttle works. In my case it has nothing to do with the vacuum actuator, the problem is that the secondary butterfly shaft was seized. I understood that the secondary is mechanically prevented from opening until the primary throttle is open. What I discovered today is that if the secondary doesn't open AT ALL, another interlocking cam mechanism prevents the PRIMARY from opening all the way. Not sure why they would do that, but that's the way it is.

I will beat this thing! Thanks for the encouragement.

@Pennyman. Yeah, I was thinking a full rebuild is not a great idea in my current situation.
It's great to have a name, but how do I contact Mike Warme? (I don't do FB, perhaps you could PM me his email?).
Yeah, it has to look like the original. That's why I was talking about taking the anti-tamper shield off my original carb and swap it onto the rebuilt. I'm not sure every smog tech will be that thorough, but some might so I would probably take the trouble to do it.
No one is trying to sell me a non-CA carb, I just found the rebuilt available, in stock, and it is visually IDENTICAL to my carb except for a couple of things I think I could correct pretty easily.

@Xbox, it doesn't have an O2 sensor, this is not a feedback carb.
Thanks for the contact. That's what I need - someone who really knows these carbs, including California emissions.
Sure, if I can find a good rebuilt carb exactly my model, I will buy it.
I haven't seen anything online so I need the contacts of where to call.

UPDATE:
I am stubborn and I like to learn stuff. Today I couldn't wait for your replies. As I said the secondary throttle shaft was seized, hard.
I figured this carb was probably toast anyway and I can't make it any worse. So after a few hours of effort, with no guidance from any manuals or carb rebuild kit instructions, I figured out how to get the secondary shaft out.
(Partial disassembly of the primary throttle shaft was required).
I had to use a punch and hammer to drive the shaft out, little by little - it was that stuck.
But after cleaning shaft and bores, and a little grease, it turns smooth.
Might be able to save this carb, after all.