The first thing you want to do is get a birthday button. They are free at City Hall. This will normally get him a phone call from Mickey or Goofy singing Happy Birthday. My dd loved this! If ds is not with you at City Hall when you pick up the pin, you can ask at any shop and they should be able to do it for you. A CM in a store noticed dd's pin and asked if she'd gotten her phone call yet.
Make a PS for a character meal. Let the reservationist know there is a bday, also let the maitr'd or waitress know. There should be Mickey confetti on the table, and they will give him a free cupcake.