Is there any documentation for the new local mode

Everything I have found on the web assumes that files are stored in the cloud. For example:

The online docs say that if you import photos from LR Classic that a local copy of all of the photos is made. Is that true if I import from LR Classic in local mode? If so then using LR CC is impossible.

LR CC does not support hierarchical keywords. What happens to keywords when you import from Classic?

What are the parameters by which you can search in LR CC in local mode?

If there is no catalog or other index, how can you search 100,000 photos in a reasonable time? LR CC can't be doing a disk scan because that would be unacceptably slow?

Thanks for any any information you can refer me to.