You are a sweet sister to make sure your brother has a great bday!!
1.) When you check in to the Wilderness Lodge - tell them you would like a birthday button for him (they are the same all over now) they will write his name on it. Have him wear it the whole trip! Characters and cast members and even guests will always wish him happy bday. (unless he is really shy).
2.) You can get him or make him a autograph book for his bday and have all the characters and even servers or guests who make his day special in line sign it - or a tshirt they will not sign on his body so bring a clip board - elastic band to secure it and fabric markers then he could wear the t shirt when he gets home. I just come home and spray it with scotchgard fabric protector so it doesn't fade in the wash.
3.) Go to the Barber shop on Main street in the Magic Kingdom and get his hair done they will cut it if need be and add color streaks, glitter, and sometimes a hidden mickey in colored hair gel. Prices are reasonable.
4.) Take lots of pictures either by your family or have a photopass photographer take them you can order a cd of the photos after the trip its about $125 + shipping and can hold 300 pictures. You can also ask a cast member to take pictures for you so the whole family is in the picture.
5.) If your going with the Dining plan the cake might be a bit much. You can order ahead of time there is a birthday cake thread if you search and it has pricing and phone numbers. If you order at the podium when you check in it's a 6 inch and the icing isn't the best taste.
6.) You can have your parents go to the
disney store if you have one close and buy small gifts that he would like and leave him a small gift everynight or morning from his favorite character. We do this with a t shirt, stickers, magic towel. Saves some $$ but he feels special everyday.
I hope your family has a great trip and your brother has a great bday!!!!