Check out this site, it may help you with meal ideas. I have purchased a few of her menu plans (very reasonable, low cost) and they have been great. She uses almond flour too but says you can sub with any nut/seed flour which you can make easily at home.
I am thinking the sugar cravings must mean yeast overgrowth? Crackers, cookies, chips need to just not even be an option, get them out of your house, that's what we had to do. Our kids have gradually adapted to fruits/veggies. Keep trying many different things, eventually he'll like something. I know kids can be stubborn but the worst thing to do is give in.
I am thinking (and maybe Dr. O can weigh in here) that once you get your son completely gluten free, and his gut heals that some of his other intolerances will go away and it will be much easier for you. What about probiotics and/or digestive enzymes for him? I'm not sure what chelating is, sorry.