The archive owner can not change any of these and must contact the site maintainer for any changes. No user will ever have to know this. The actual path is not needed in any user requests. Only archive subscribers, the archive owner and the manager will see the archive. The archive is stored in UNIX Compress format.
Compression is transparent to end users as the file is uncompressed before being sent to users.
The files in the archive are stored uncompressed. Listproc can compress files to better use disk space. This would be transparent to end users. The files are not split regardless of file size. Listproc can split up large files into predetermined pieces.