Hi @ksbaig_cesium ,
Thanks for your post and being part of the Cesium community.
This previous forums thread covers how to place a dome on the globe in CesiumJS How would you make a dome or semi-ellipsoid?. Hopefully that is a helpful start.
I am not sure what you are looking for in questions 3 & 4 in your post. If you are still looking for help on those specific details, can you please provide more details on your use case?
Best,
Luke