Auto-Sync issue...

if I auto sync an auto-straighten adjustment across multiple pictures... I think it changed the angle on all of the pictures to the same as the 1st picture... not 'auto' anything across all the pictures.  So strange!

In Synchronize Settings (or Copy Settings, or defining a preset), make sure Upright Mode is checked but the other two Transform settings are not checked:

That will recompute the auto transform for each photo individually. 

If I select multiple pictures, say 100, and auto-sync auto "tone" - it will auto-tone all 100.  Works fine.... But then if I go to any of those 100 individually, and hit the AUTO (tone) button again... the toned settings change again!

If you really are using Auto Sync (and not Sync), then minor differences between batch application of Auto (via Auto Sync or Library Quick Develop) are to be expected.  According to Adobe engineer Simon Chen, for performance reasons, batch Auto uses lower-resolution versions of the photo stored in the Camera Raw cache, and the Auto algorithm will give slightly different results than when it is applied to a single full-resolution photo in Develop.   I did some small-scale testing of batch Auto and generally found the differences very small, but did find one photo (out of seven) for which Exposure was +0.86 versus +0.64, and to my eyes, that seemed significant.

If you think the differences between batch and Develop auto are not insignificant, please continue the conversation in the bug report in the official Adobe feedback forum, to ensure that the conversation remains focused in one place: Auto Tone of a batch of photos gives different results than if you do them one at a time | Photoshop Family Customer Com… .  Include links to the original photos via Dropbox or similar so Adobe engineers can see what you're seeing, and be sure to include the first ten lines from Help > System Info.

If applied in the Develop module to multiple images, the most selected image is the image the auto tone gets based on for all the images.

If you do this in Library module (quick develop), the auto tone gets applied individually to each image.

So, accomplish this in the library module

Note, that this is not exact, you may find some of the images are not spot on, and if you try auto tone in the develop module (to just one image) the values may changed. Probably due to difference in color space between Library and Develop.

One link, although I think not the one I first learned this from:

https://blog.thomasfitzgeraldphotography.com/blog/2018/1/applying-lightrooms-auto-settings-to-multiple-images