I'm the "queen of food allergies" as my husband calls me.
I'm allergic to all tree nuts, coconut, water chestnuts, scallops. In the past year I've also developed a sensitivity to peanuts. It's not a full blown allergy, yet...but that's the way all my food allergies have started.
At any rate...fear not.
I don't bother to have the reservation noted, the server and chef getting the info is slim to none. I also don't call in advance, except for pre-plated limited menu places, like the Hoop De Doo Review (which safe for me). Boma is a very scarey place for nut allergies, and I would avoid it at all costs.
WDW uses Canola oil for all frying at all restaurants except some foods at Jiko and CG. No peanut oil unless specifically stated otherwise.
Here's what you need to do. When you are seated, let your server know your son has food allergies and you need to speak to the chef before ordering. The chef will come out and speak to you. Do NOT rely on the servers. I had one suggest pasta with a pesto sauce would be agood choice for me. (duh--pesto is walnuts!) Buffets can be tricky, insist on speaking to a chef, and not just the guy on the food line fillling things...they generally don't have a clue.
Is cross contamination an issue? Aerosol contact? If so you need to be doubly careful and remind the chef's of this. (Cross contamination is a huge problem for me, but aerosol and epidermal contact aren't so I can't comment on those two.
Good luck and let me know if you have any other questions.
Anne