I really appreciate everyone's input and advice. It helped boost my confidence which was sorely needed doing something like this because I really was worried that I would wreck them trying to fix them.
Here's a before/after. I have not yet starched them post cleaning. I'm looking into some ways to do that best, since a few of them are so...so many bits! I really am in awe of this work, especially the size and detail now that I've spent so very much time fussing over them.
One thing that has come out of this "oh noes!" and back again, is I now love these ornaments even more. When you have to seriously look at all of the joinery and fiddly bits within each flake, it's something to behold with respect.
The main reason I put the after on the bathmat is because when I had them on a white towel, it was much harder to see some of them because they are much closer to their original color.
You can see where the ornaments that had the worst of it still are not quite remedied, but still better than before.
First, I rinsed them all with warm water. I did not use any soap because I feared it would cause more trouble than it was worth.
The rinsing did reveal one important thing to me: the starching actually prevented a lot of damage to the ornaments. I meant to take a picture after just the rinse, but some of the ornaments already looked worlds better just from that. The ones that were evenly starched (I could tell by how much was coming off as I gently rubbed them between my fingers after about the second or third ornament) were in the best shape.
The angel has some stuffing in the head for shape. I don't know that it is part of why the angel got it the worst or not. I suspect it's possibly that the stuffing retained the moisture that got into the box, but it's just an educated guess.
I had done a test with two of the smaller snowflakes, one with the lemon mix I found, one with just peroxide and water dilution. The results honestly were so close, it just made more sense to use the peroxide and water.
Worth mentioning:1) I double soaked the worst of the ornaments. Two nights' worth with a rinse in between. There was a noticeable difference. I am tempted to do it again, but what I decided instead was to set them aside because of the deterioration I found.
2) I assumed the acid in the lemon was harsher than the peroxide. I'm still not sure that this is 100% true, and am not willing to take the time to do proper research either way.
I noticed on two ornaments that I later treated with an overnight soak of peroxide and water that I could see some deterioration, which made me question my choice. Writing this up now, I realized that before cleaning I did not think to examine the ornaments for natural wear and tear, so the damage may have already been done beforehand.
I realized the damage was where the hook goes, and only on those two. So although it may have been more wear and tear on those areas due to the hooks, or the material was broken down because of the peroxide, I don't know. The one that seems the worst off, I'm going to try to do a mend on, but I have no idea what to use, as most of my threads are at least partial poly something or other. So I'm going to wait until I can research this a bit more.
Here in Gardner, when the weather is warmer, the local community center has some days where crafters can come in to craft together. One day is specifically for stitch work. So I'm thinking I might set the two that need the repair aside, and when the crafting days start again, I'll take them with me and try to see if I can plumb the knowledge of the local elders I know will be there.
3) The angel is really the one I fret about the most. It doesn't look as "Angel in the Mud" as before, but it's still off. So I'm hoping that when I pull them out again later, my perspective may change as to how I feel about the look of them.
you can get the little litmus paper test kits for a couple bucks. 
But you're right in that maybe I shouldn't destroy them in the pursuit of whitest white.
