While working for Amos Press, Rulau edited publications such as Coin World and Numismatic Scrapbook. He was also responsible for creating World Coins Magazine.

He later worked for Krause Publications, and contributed to the editing of the World Coin News and Bank Note Reporter. He has also written several numismatic books, including How to Order Foreign Coins, Modern World Mint Marks, World Mint Marks, Hard Times Tokens, Early American Tokens, U.S. Merchant Tokens 1845-1860, U.S. Trade Tokens 1866-1889, Tokens of the Gay Nineties and Latin American Tokens. For many years, he also served as the North American representative for the Pobjoy Mint.

In addition to the American Numismatic Association, Rulau is a member of various other numismatic groups. These include the American Numismatic Society, Royal Numismatic Society and the Royal Canadian Numismatic Association. He is also a recipient of the Numismatic Literary Guild's coveted Clemy Award, and several awards from the American Numismatic Association. These awards include the Glenn Smedley Memorial Award, Lifetime Achievement Award and Medal of Merit.