Macaws eat a lot of fruit in their natural habitat and just bananas isn't going to be enough, he needs a variety and I worry that just bananas might throw the balance of potassium off in his body. Too much of any one vitamin/ mineral is just as bad as not enough of it in terms of his health. Try adding apples, oranges, strawberries, cantaloupe, mangos, pears, kiwi, but stay away from avacados as they are toxic. Macaws also eat more tree nuts than many other species of parrots so try almonds, hazel nuts, brazil nuts, walnuts, pecans and such, peanuts are not nuts they are a legume.
You are at that point in the cycle of his life that his parents would be teaching him what foods to eat, how to eat them and where to find them, so this is the best time for you to teach him to eat a large variety of fruits, vegetables and nuts. The longer you wait to do this the harder it becomes to teach them to try new foods.
I really don't care for pellets and zupreem would be among my last choices for them if I fed them as they are known for using inferior ingredients in their parrot foods. I feed gloop which is a home cooked food that consists of about 40% partly cooked whole grains, 40% mixed vegetables and 20% fully cooked white beans and lentils. I get the whole grains from a health food store, the mixed vegetables from the frozen foods at the grocery store and the white beans and lentils from the grocery store as well. There are some recipies for gloop in the health, nutrition and diet section. Gloop is a soft food with plenty of moisture in it and it is what I feed all of my birds for all day long and it should be very easy to switch him from formula to the gloop.
I also feed a good quality seed mix and a few tree nuts to my birds for their dinner and then remove them when the bird goes to sleep at night.
I have never noticed a smell from my birds poop unless they are sick, but keep the peace and increase how often you mop the floor, just be careful of what products you use to clean the floor with as some of them are toxic to birds. Read this link, there is a list beginning on the second page that lists foods, plants, trees, woods and household items that are safe and toxic to your bird.
I hope this helps you.