which rsync command?

[David Epstein]

All the files and directories I want to talk about are on the same machine (a Mac).  I have a directory that I will call SOURCE. This contains a a number of files, some of which are directories containing further files. I want to copy these files to another directory, which I will call TARGET. Please assume that SOURCE and TARGET include absolute path-names. I think they should also end in a slash (subject to correction).

If a top-level file/directory is present in TARGET, but not in SOURCE, I do not want it to be disturbed.
If a top-level file/directory is not present in TARGET, but is present in SOURCE, I want it to be recursively copied into TARGET
If a top-level file/directory is present in TARGET and also present in SOURCE, I want it to overwrite, so that the ccorresponding file/directory in TARGET at the end of the rsync job is a copy of what is in SOURCE, with the same permissions and date-stamps.

Since it’s on a Mac, I also want to transfer extended attributes.

I would be grateful for the recommended recipe. 

Would dry-run tell me what rsync proposed to delete as well as what it proposed to install. It’s because I don’t understand the option dry-run fully that I’m reluctant to use trial-and-error to get to the right command.

I think I would have to use “sudo” since some of the files are not readable by me when I am an ordinaty user.

Thanks