Does it matter what order ingredients are sauteed in?
Your first suggestion is only partially valid. Let's say you add your onions first as many would do. After that your stew as a whole will most likely be too wet to get a maillard reaction going for subsequent additions. For me, the order of additions to a stew is roughly determined as such:


Put the ingredient that you most want to caramelize in first (usually meat or onions, but never garlic)
If you have ingredients that transfer their flavour more easily to fat than water, always put them in early, because once your stew becomes more watery that flavour will no longer be transferred
Put items that rely on their fragrance in late (For instance fresh basil)
Bell peppers always go in late for me, but that is partially because I always peel them
Give everything a cooking time that allows the ingredients to transfer their flavour to the stew while also maintaining some texture (basically your second point)


In the end it all comes down to adjusting your process so that everything you add to your stew is able to do what it's there for, which might be adding flavour, texture, colour, wetness or anything that takes your fancy.