Development of a new segmentation workflow for a certain bone image, acquired with a specific imaging protocol, for a specific application always takes some time and practice. If the generated mesh surface looks good then segmentation task has been successfully completed. You may post an screenshot of your segmentation if you are not sure if the quality is good enough and we may give advice on how to improve it.
By default a coarse mesh is generated so that you get result quickly. Increase --scale parameter value in Advanced settings section to genereate a finer resolution mesh.
Cleaver generates a “background” mesh so that you can simulate embedding your structures in some material (soft tissue, etc). If you don’t need these mesh elements, then don’t use them. Each cell is assigned to a segment, specified by labels cell attribute. You can use this attribute to assign material properties or remove parts of the mesh, etc.
There is no video tutorial for Segment Mesher, but it would be greatly appreciated if you created one about your workflow, once you’ve figured out everything. You can of course post any specific questions here.
It is not. 3D Slicer is very capable.
Use any tool that work for you. Probably segmentation tools of Slicer are better than of Mimics, but Mimics has probably more meshing options and direct exporters for FEA software. So, if you and all your users can afford to buy Mimics then of course, give it a try. You may also try to export surface meshes (in STL, PLY, etc. format) and let your FEA software generate the volumetric mesh.