Dear Parinaz DM shared topology was unreliable for me also, use SpaceClaim. The Share button on the Workbench tab is very reliable.
The solids are renumbered in DM when you Form New Part or do a Slice, so Mechanical entities scoped to them will have to be repaired. The same thing happens when you use SpaceClaim.
Yes, in DM, it is Concept, Slice. In SpaceClaim it is Split Body, but you have to make a Plane first.
After configuring the slices to use a Sweep Mesh Method and putting Face Meshing to force hex elements, the Edge Sizing has a Bias parameter in the Details window.
Regards Peter