I deleted my first reply to this message because it was based on your initial version of the post that didn’t have any tutorial links in it, yet. Had those tutorial links been in the first or second message it would have saved a lot of back-and-forth.
Having seen what your questions relate to, I’ll try to answer your questions:
Question 1: “Should I eyedropper-WB the CC image before or after exporting it?” This refers to the Export using the CCPP export preset that creates the custom color profile based on the CCPP image.
You can eyedropper the WB of the CC photo before Exporting it but you don’t have to. I do eyedropper my CC image before creating the profile so I know what WB the profile is being created for. This is useful to me in naming my profiles as well as useful to see if I’m creating a redundant profile, one that I’ve created for very similar lighting from a previous photoshoot. I initially created maybe a dozen custom color profiles based on different lighting scenarios and I still shoot a CCPP when I think I might be in novel lighting, but I rarely create a new custom profile because the lighting scenarios are pretty much covered by my previously created profiles.
As far as eyedroppering after, you do need to eyedropper some neutral color somewhere in your images to synchronize the rest of the images to but this is not related to the process of creating the custom camera profile despite the two things being shown back-to-back in the first tutorial, it is related to wanting your WB to be right regardless of whether you’ve just created a custom profile or not. If your CCPP image is large enough then you can use the next-to-white patch as an eyedropper WB neutral area. If you are shooting at more of a distance then maybe use a larger neutral target such as the other white-only CCPP page.
The first tutorial also shows how to tweak the WB a little by eyedroppering on the slightly bluish patches to warm on the portrait photo or by clicking on either the slightly more green or slightly more magenta paths to warm up or cool down a landscape shot. This is not setting the initial WB, it is tweaking the WB or adding a slight color cast to warm up or cool down your images. I don’t use these WB-tweaking patches at all but in a tutorial about how to use the CCPP it is good to show them being used so you can understand what everything is for.
Question 2: “If I export as DNG and open that DNG in PS-ACR, do I need to eyedropper-WB, again?”
The answer depends on if your DNG already contains the development settings you applied in LR or not. If it does, then the WB you set in LR should get picked up and used so no need to WB, again, but if upon opening your DNG in ACR you see the default WB such as As Shot when you know you’ve applied a custom WB in LR, then you probably need to figure out why the LR WB isn’t transferring over, rather than redoing the WB in ACR. If you are using a plain raw file and not a DNG, then the LR settings can be saved into an XMP sidecar file next to the raw file of the same base name. Those XMP files can either be created automatically if you have the preference set to do this, or can be created explicitly with a Save Metadata to Files command from either a right-click menu or using the Metadata menu item.
Are you asking this second question because you’re not seeing the custom WB set in LR carry through to ACR?
Some more comments about the tutorials. I wouldn’t stand so close to my model to shoot a custom WB because I’d be concerned I was blocking the light and changing the ratio of ambient to flash and therefore change the color temperature by standing so close.
Another issue with at least one of the tutorials is that when they are synchronizing the WB across multiple images they are leaving too many other checkboxes enabled. If I was merely trying to synchronize WB then I’d probably enable only the WB and Calibration checkboxes.
My suggestion about what to do for each lighting change is to shoot a CCPP, a CCPP-neutral page, and maybe set your camera’s custom WB to that CCPP-neutral page. After importing the images into LR eyedropper either the CCPP or the CCPP-neutral page and then synchronize the other photos in the same lighting as those to the reference image. Once you know what the WB is, then scan your lists of existing custom color profiles for one that is close. If there is then use that custom profile, otherwise create a new custom-profile. Now you see why I want to put the WB numbers as part of the name of the profile, so save myself some work and clutter if I really don’t need to create another profile because one already exists. TO summarize, you don’t necessarily need to create a new custom color profile for each lighting change, but you do want to re-WB a reference and re-sync that to the others in the same lighting.