Elrian: Then did Tolkien mean 'Dwarrowdelv' when he wrote 'Dwarrowdelf'? Or 'dwarv' when he wrote 'dwarf'?
There is no pronunciation guide for Rohirric or the related old northern languages in the appendices of LotR, because those languages were Old English and related old Scandinavian languages. The appendices deal with Tolkien's invented languages only (you'll note that all the example words are Elvish, Khuzdul or Adunaic).
Take a look at the
entry for Gandalf in the Encyclopedia of Arda, if you don't want to take my word only for this.