I found a lady in George(SA) that is writing a book on the Nel surname history. She will no doubt be able to answer many of your questions, and would also like to have your own information for her book. She helped me to link up our own family tree!
Her name is Corrie Nel-Henry, and you can contact her on firstname.lastname@example.org
I also have a gendac/paf file with a lot of the Nel history that I got from Hennie Nel. It is 1.5 M, so let me know if you would like to have it.Mail me on email@example.com