The dress code has been relaxed at the signatures. Shorts have always been allowed, they just can’t be cut offs. Tee shirts are now allowed, just keep the graphics under control, that is, no “Big Johnson” tee shirts, etc. Personally, I feel solid neutral color tee shirts are fine, that is, earth tones, black, some blues and reds, especially pocket tee shirts. Usually I’m wearing a pair of Columbia Sportswear cargo shorts and a tan Russell pocket tee or a Polo type collared shirt and I fit in just fine. If wearing jeans, I wear my blacks, not blues. Wear a nice pair of running shoes or walking shoes, not sandals.
As for menu, there are beef, chicken, and pork dishes on the menu, so don’t worry.
For fireworks viewing, I have always preferred to go outside to the north observation deck, which also has speakers that usually carry the show soundtrack and this will allow you to hear the bursts as well as see them. Another thing to consider, at a table, someone is always going to have to turn their chair to watch, and really, who can eat during Wishes?
If however, you want to dress in suits and cocktail dresses, you won’t feel out of place.