Hi brani, so nice to meet you, and
to NGA and the Sempervivum Forum.
There will be others chiming in to answer some of your questions.
On your question about the gravel/chicken grit, it is placed as a top dressing and under the leaves of the rosettes to keep the plant from coming in contact with the soil. In some cases the soil can cause the rosettes to rot. Remember these are alpine type plants and are used to growing in fast draining soils with lots of rocks and crushed rock content.
We would love to see photos of your semps.