Compute magnet and rotor losses in a 3D simulation

Hi everyone,

I would to compute the magnet losses on a SPM machine.

The magnets are axially divided into several blocks in order to reduce the eddy currents circulation. 

The rotor yoke is also axially laminated with several axial slices.

I found the application note of the IPM motor in order to create the 3D model with several blocks. 

I have some questions:

1. Can i extrude different face regions with different lengths?
2. Do I have to define an airgap face region between two magnet axial slices in order to compute the insulation between the magnets and reduce the eddy currents circulation?
3. Do I have to define an airgap face region also for the rotor yoke axial slices and assign them on the faces between two slices?
4. If I want to extrude a face region multiple times across one direction, how can I do? Do i have to set a offset value on every extrusion or do I have to assign the face regions to the new faces on the new volumes created and then extrude them? 

In addition, I tried to model this motor once, by starting from a 3D CAD, with airgap face regions between the magnets slices and the rotor yoke slices, but i get this message:

"The coupling with neighbouring volume regions of faces:
363 340 317 294 271 248 225 202 179 156 133
of face region ROTOR_AIR is forbidden.
The coupling with neighbouring volume regions of faces:
107 102 97 92 87 82 77 72 67 62 57 53 49 45 41 37 33 29 25 21
of face region MAG_AIR is forbidden."

I removed the airgap face regions but I get this message:

"The group of volume regions:
- STATOR
is multiply connected (have hole(s)).

There can be a problem called connexity problem if a coil forms
an interlacing with the group of volume regions.

If you have a connexity problem, you must create a cut of
magnetic circuit which cuts the group
of volume regions.
It has not been possible to automatically set formulations
to regions.
You must assign yourself the formulations, choosing a
formulation model different from "Automatic formulations", as
follows:
- menu: [Application] [Edit current application]
- in the dialog box, click on the "Formulation model" tab,
- choose a formulation model different from "Automatic,
formulation"

Thank you for your kindness.