The surname Vang has significanse in Denmark. It means glade or garden and was used in the first translation of the Bible to Danish as the Garden "vang" of Eden. The town of Vang on the Island of Bornholm has a very colorful history. I guess the purpose of these ramblings is that you may want to look, geneologically, beyond Norway.
I would be interested in your results if you have time, or a question, please give me an e-mail.
Sincerly
Freddy Vang