Got it. DKIM works now. I had copied a wrong key-pair (from a certificate). Here is how I generated the working DKIM key-pair...
openssl genrsa -out private.key 1024
openssl rsa -in private.key -pubout -out public.key
I may switch 2048 or higher, but my DNS host requires breaking up into multiple records.
Now I have DMARC working also.
Thanks again.