T.,
Since you're utilizing formula and not breast milk, you would think of the formula in much the same way. Most of your son's nutrition will come from the formula for the first year of his life. Food at this age is more for texture. If your son shows signs of being hungry after drinking his formula and then eating the food you offer, just offer more formula. But always offer the standard amount of formula at the beginning of each meal as you do now.
As for juice, it holds virtually no nutritional value for your son and honestly should be avoided. Even though it contains natural sugars, it's far too concentrated, and not the best option nutritionally. Offer him fresh organic fruits instead. Think of it this way ... if you took one whole apple and juiced it, how much juice would you get? A lot less than the suggested 4 oz. Better to offer fresh fruits and vegetables than to offer concentrates. And stick with formula in the sippy for now. You'll want to maximize on nutrition right now, and water holds none. Let him hydrate from the formula.
You also mentioned wheezing. You may want to consider stopping the cereal altogether. Focus on egg yolks (warm and soft, but not runny) and those fruits and veggies. Grains from the cereal may be causing some dietary trouble and contributing to the wheezing (i.e allergies). You could even try organic yoghurts (Stonyfields or Seven Stars whole milk are great choices. Always choose plain when you have an option) as a way to add some good probiotics to his digestive tracts and help him digest all this new and wonderful food.
Best of luck, and blessings to you and your little one.
Rolinda,
Wife, Mother, Friend