As I recall, in addition to iClone you need 3DXchange Pipeline to enable the export capability. This was the case for iClone 6 and hasn't changed as far as I know. But better check with RL directly.
An Alembic file does not include textures. It exports the geometry as a point cache, and textures need to be assigned separately. I believe RL has done some work to make it easier, but it does require also exporting an FBX version, which gives you the textures.
Displacement is a texture effect, so it would not be part of the point cache, I believe. The mesh is changed dynamically, so you would need to bake it somehow to make it permanent.
EDIT: Just read a more knowledge post about Alembic export here:
https://forum.reallusion.com/FindPost389098.aspx. FBX export is no longer required, apparently.