What if I have Chaos Form in my hand, with the required materials but Chaos MAX is not in my hand. Can I summon it from the main deck?
No you can't. This simply isn't how ritual summons work. Unless any card states otherwise (e.g. the nekroz ritual spells) you must tribute monsters from your hand or field to summon a ritual monster from your hand.
In general you cannot interact with cards in your main deck, unless another cards specifically states otherwise.