Malo

Yes, the term "layer" is more then on contex in that product.
But they did nearly all the same, They store informations separatly of the whole object.
 
Paint Layers - Like in Photoshop, Gimp or any other 2D Painting software.
Retopo Layers - You could retopo, shirt, shoes, pants, body, eyes, teeth and so on on differnt layers to easy hide parts of your retopo.
and they help you with baking if you want to bake more objects at ones without touchung each other.
Vox Tree Layers - These are for sculpting separate parts of your model. I think they are called SubTools in ZBrush. You dont have to sculp shoes and pants at the same time.
Sculp you pants on one layer and then on a new layer sculp your shoes. If you need changes on one of the objects, you dont change the other ones.
Very handy overall while sculpting. For your other question, why 3d coat dont create a new layer if you use a primitive, is very easy.
How should 3dcoat know what you are trying to do? You could join it with the models on the same layer or is it a new object, who knows?
Its the same in Photoshop, If you change the tool or color, a new layer wont be created automaticly.
Vox Layer Tool - A tool to create a new objects based on the surface of an other object with thickness.
Sculpting Layers - A Tool to create extra details on your object without destroying the old object. Delete the layer and you have your model untached befor sculpting. Nearly the same way as in Mudbox.
 
I hope i dont miss one

If i remember correctly give your objects individual materials and export it as obj or fbx.
Then import it in 3d coat.
At the start up, you have the option to change resolution for each extra material group.
 
It is not a big deal to work with multible objects in 3d coat.

What you did in Blender is possible in 3d coat.
 
1. Open your Object in Paint Room and load in your textures.
2. Switch to UV Room and create your new UVs.
3. Klick on Apply UV-Set
4. Switch back to Paint Room and it is done.
 
Much easier as in Blender.

Use a negative value for the zooming speed in preferences.

1.
UV-Room

Klick on the little dropdown menu and choose what you want.
 
2.
After baking, you get your model into UV-Room.
 

You are in Voxel Mode.
Voxel works different. You model gets calculatet new with triangles.
What you did is the normal way how it works in Voxel Mode.
 
For your needs, you should start with Surfacemode.
In your import options, check import w/o voxelization.
That should bring in you model with you real polycount from maya.

Take a look into the Preferences under Viewport.
There is an option for the Camera Zoom Speed. Set it to -1 (negative value) or what you like and it is inverted.

In PaintRoom
Edit-> Sync Layers w/ Ext. Editor or
Edit-> Edit all Layers in Ext. Editor
 
You get a bunch of Layers in Photoshop and one of that layers (the last one) have the wireframe included.
You have to set your Path to Photoshop first in the Preferences. Edit-> Preferences-> General-> External 2D Editor.

Did you search for the Snake Tool?
Scroll a little bit down, you find it under Objects.

Little tutorial
 
Retopo Room

I have 3 UV sets and one retopogroup, but that makes no difference if you need more.
 
Baking options

You see, i get 3 UV Sets (Bust_head_bottom, ...._right and ..._left) and my Baking Options.
 
Paint Room

Now i have 3 Surface Materials, that is important.
 
Export

My export options.
 
Substance Painter

You see on the left 3 texture sets and i could hide it on the right side.
 
Maybe that helps.

I show you what i mean.
 

 
Hope that helps more.
But sure, you could export and import it if you like that more.
 

Hold ALT while you want to move, zoom or rotate.

I was thinking you want to use your gear from the images.
And they looks very open to me, not closed.
If you import a object like this into Voxel Room, it gets closed, sure, but maybe in a ugly way.
 
I cant show you some pictures or video, i still cant go online at home.
If you have time, i could explain it more detailed.
 
But for now
1. bring your object to VoxelRoom.
2. enable radial symmetry with 8 areas. (one for each tooth)
3. adjus symmetry, maybe your object is not at center or something like that.
4. use posetool with one of the first stroke modes from E-Panel.
5. make a line from the top of the tooth to the bottom. you will see a masked area with gradient.
    or maybe from bottom to top, i am not sure, i cant test it right now.
6. align the gizmo to the correct space in room, that you could easier move it around.
7. move the gizmo
8. if movement look weird, restart at the point 5. (new line, align gizmo, move gizmo)
9. and so on, until you are happy.
 
That should be it.

Disable Displacement
Paint Room -> View -> Uncheck Show Displaced Mesh
 

Turn on symmetry.
There are some options for radial symmetry.
 

 
This should helps you.
 

After a look into the file, is see that you have many holes in your Surface.
Looks like Auopo have some problems with that many holes.
 
There are two quick workflows for your problem.
 
1. Duplicate your Surface Object, convert it to Voxel and use that Voxel Object for autopo.
You could delete it after you are done with autopo.
 
2. use Voxelize before Quadrangulation.
 

 
Version 1 have more controll over the object. You see what you get for autopo.
Version 2 ist an automatic option, less controll at all.
 
I hope that helps you.

The best way is to do it by hand. Surface mode and the Clean Clay Tool do the trick.
Reduce the polys only in that areas that are needed, without loosing dedails.
 
If it makes no difference if you loose details, then it would be easier if you resample your model.

After choosing your file for import, a new windows gets open where you could scale, rotate and do other stuff.
In this menu, simple click on Reset Axis and Reset Space and then scale your object to your needs and hit apply.
 
If that wont helps, check your export options where you have createt your file.
Maybe it is out of center or gets after export.

Layers are fine, because Painting in 3d coat works like in Photoshop.
 
Export is easy
File -> Export Model -> choose what you want and hit OK.
Dont forget to use Padding.

Waiting for a fix.
It is broken since a few builds.

The scale is only visual. You could scale it as big as you need, to work with it.
If you export your model, it would be "rescaled" to the original size.
 
You should be sure, you have applied your model after import, and switched to a different tool as the merge tool.
Then you should be able to change the shader.

If you want to bake it.
Give your Highpolyobjects the correct shader or polypaint should work, too.
Try this
http://3d-coat.com/forum/index.php?showtopic=14921&page=2
That are shaders for PS and ddo to bake material IDs. I think after baking it is possible you have to swiitch the blendingmode to Standart instead of multiply, its a while ago i have testet that shaders.
Or create it by your self. Use the default shader and change it to the color you want, 100% blue or red or what you need.
 
If you want to paint it.
Merge your lowpoly into the paint room.
Delete or hide every created layer in paintroom, keep only Layer0 and Normalmap and Bakedocclusion.
You could delete BakedOcclusion too, if you dont need it for your workflow.
Then paint you object, uvshells and stuff in the color you want to use.
 
Take a look at this.

 
At 50min you see how i did create the Material IDs.
If you paint it, and want to export your textures, disable BakedOcclusion thats important. Without that, the AO gets exportet into the color and your clean Material IDs are broken.
 
 

Screen?
 
1. Start with Paint directly ove UVs
2. Merge Object

3. Switch to UV Room
4. Change UV Set

5. Mark all UVs

6. Move to first Uv Set

7 Switch to UV Set 1

8. Done
 
Now Apply your UV set to save the changes
Paint on it.
 
Hope it helps.