I just installed this in Blender, and it looks great! I'm new to both CC3 and Blender, though, so I'm not sure how to solve certain issues I'm having.
The first is that in exporting an FBX to Blender and then importing it with CC3tools, the clothing seems to shrink slightly, and there is poke-through where there was none in CC3. Is there an import or export setting I should use to prevent this?
The other is that, while everything seems to render pretty well in eevee, if I switch to cycles, shadows take on hard edges along the quad edges. I'm pretty sure I'm just missing something obvious here, but in Blender nothing is obvious...

It is one of 2 things.
1. Your character might have body subdivided in CC (this smooths and shrinks it a little bit). But while exporting subdivision is disregarded so the skin might poke through. Make sure to fit cloth on the Original body - without Subdivision, nor Tessellation.
2. This is most likely the cause. You might need to reapply skin weights. Here's how I fix it:
After everything is conformed and looks good in CC:

* Disable Conforming for each cloth item.
* Convert cloth to accessory while selecting "Bake Current Shape".
* Transfer Skin Weight for each item.

If there is still minor pocks in Blender, you should be able to fix it easily by editing the mesh.

Curiously enough, baking the current shape causes exactly the same to occur in CC3. And I do mean exactly the same:

The problem in Blender:



and the result of convert to accessory->bake current shape in CC3:



The problem is identical. I believe the export process from CC3 bakes the shapes of all the clothing objects, to bake in all the clothing layers conformity and collision into the FBX, but clearly something is going wrong with that. I'm calling this a bug in CC3.  Edit: it's just the hidden faces showing through, see post below...

In Blender I fix these problems with the sculpt tool. The 'Elastic Deform' sculpt tool works wonders.

For some cloth items you have to do it more than once

Do exactly the same thing twice and for all cloth items and it would be alright.

2 passes of the same routine:





Still manual tweaking is necessary even in CC for various poses until all is OK

Ok, it's not a bug, I know what it is now.

Some clothing items selectively hide the faces underneath with the "Hide Body Mesh Tool", when you convert them to accessories or export them to Blender, that information doesn't carry across, unless you tick the "Delete Hidden Faces" in the exporter.





I really should read the instructions some day.

Thanks, you two. Only now I have more issues.... 

First, the CC3 figure's bones don't seem to operate properly in blender. Do I have a setting in CC3tools wrong? I think I'm running it default.
Second, Rigify has a posing armature that works much better than anything in CC3 or the native translate/rotate tools in blender, but I haven't been able to figure out how to apply them to the rig from CC3. Is there a way?
Third, I've attempted to simply remove the CC3 bones and start over with Rigify, but this is a VERY tedious process because the character mesh resizes itself times 100 when the bones are deleted, and Blender's process for return it to the right scale and position seem to be pretty lousy. Is there a way to remove the bones without blowing up the figure?

I probably sound like I want everything to be easy- because I do! I have to process a LOT of characters for the projects I'm working on, I need to find a reasonably efficient workflow.

Thanks in advance for any help.

I think you could try autorig, which is an add-on that does a lot of the work you're asking for here. Not sure if Victor plans to add the character rigging automatic setting in his add-on, then as you said, it's quite a tedious work and there are already other add-ons out there for that purpose.

I came here after watching this video and Victor gave us a lot of useful on information on how to do the first part of the video in a much more extensive and accurate way, now I think you're asking for what happens in the second half of the video and that's the part I don't know if Victor plans to include in his add-on or not, but this could be a first step if you want to get your characters quickly rigged in blender

If by that you mean does it have an FK/IK animation control rig, then no it doesn't. All we get the is the bare bones and vertex weights. An animation rig, with all it's control widgets, shapes and constraints is something that has to be built around the armature and bones and doesn't come with the FBX.



I haven't got to the rigging stage yet, but it is something I hope to add to the add-on in the future. snatolukas32, somewhere in this thread did mention getting a Rigify rig working with a CC3 character so there is a way. I just don't know it yet.



This I do know: Select all the objects inside the armature (but not the armature itself), press Alt-P and select Clear and Keep Transformation, this un-parents the objects from the armature and keeps their current transformation and scaling. Then you can safely delete the armature. Best to do this with the armature in Rest Position.



One of the reasons I'm making this add-on is precisely to make an efficient work flow that doesn't bog me down for hours every time I want to do something in Blender. Not there quite yet, but getting there.

Thank you, M. Soupday.  I will try ctrl-P and just applying a Rigify armature- or perhaps AutorigPro. I really appreciate all your work and feedback.  I can't wait to see your rigging component! I will try to see if I can reproduce snatolokus32's process, too. Thanks!

Edit: I see that snatolokus is talking about subbing in a rigify rig, so I guess we're on the same track. 

@Oonabe: I saw that video, it's pretty good, but I kind of like the rigify control rig better, I think. But, I do actually own Autorig now, so maybe I'll try that- it seems like it automates a bunch of stuff you have to do manually in rigify. 
The thing about there already being other addons for that, is that they sometimes don't play nice with each other. I don't know enough about blender to know if it's a problem there, but I've seen it in plenty of commercial software that is built up with modules with different origins. Sometimes it's just a matter of the parts not agreeing on what the controls are supposed to do, or terminology conflicts, but sometimes it's more serious and you need addons to make the addons work... So, I know it's a lot to ask, but I really like it when one designer puts together as many parts of a workflow as possible- the products tend to be so much easier to use.

acutally if you are talking abt Rigging CC3 character.... (im absolute begginer in Blender - but after 1 or max 2 tutorials im able to Build , allmost working RIGGED cc3 character with 
RIGIFY) - NOT 100% working cuz i didnt learned yet how to Correctly Rig TEETH and EYES (but it is easy also, i saw tutorials , there are hundreds of TUTORIALS how to.... its Blender guys)

I can prepare a SHOW-OFF video how to use (build Skeleton) RIGIFY with CC3 - BUT IT NOT WORKS 100% it just too early for me. i Will just show You its not a DIFFICULT Process. 
You can ask Markom3D to make proffesional tutorial with RIGIFY with CC3 i think its not big deal for Him. If abt me i need to learn more to make 100% working tutorial.

To everybody... my little  suggestion is  to start learning riging from 1 - simple bone to understand everything in whole process. Actually using RIGIFIY or Auto-Rig is just for lazy ppl or for PRO who
dont have time to making RIG bone by bone. 

Ill do the video with RIGIFY but dont take this as guide/tutorial.