I would definitely add the gelatin as it is really good for you...the formula's designed to go through a bottle so I would think it wouldn't be too thick for a tube.
As for the coconut oil...are his feeds cold, warm, or room temperature? If you can give them slightly warm or at room temperature I would think the coconut oil would be fine, although it might end up being easiest to add it separately each time so you don't have to warm up the whole batch of formula and mix in the coconut oil. Or maybe you could use a blender, melt the oil, and then add it very slowly like you would for homemade mayonnaise? I don't know if that would damage any of the rest of the ingredients, though.