Let's start with your first item. Have we seen any other combonation fill ALL the properties of life? If not, why should life have ever formed from other combos, and why don't they exist today?
Sure if you spread the different combos out on all the planets capable for life, it would increase your odds, but then you have the one to a trillion trillion odds that each planet would try different combos. The odds of getting the right combo are still extreamly high.