For now, I was able to resolve
4.
-- Could NOT find NCCL (missing: NCCL_INCLUDE_DIR NCCL_LIBRARY)

This is a confusing warning, because setting the environment variables NCCL_INCLUDE_DIR and NCCL_LIBRARY does not resolve the issue. Instead, the solution is to set the environment variable NCCL_ROOT_DIR. In my case, I set it to /home/user/miniconda3/pkgs/nccl-1.3.5-cuda10.0_0/.
The other warnings are still there.