Mutations are simply too rare to have produced all the necessary traits of even one life form, much less millions. 2 - Random effects. They are never purposive or directed. A mutation is a random, wild, event. 3 - Not helpful.
Evolution requires improvement, but mutations never help anyone.
They only weaken or injure. 4 - Very harmful effects. Nearly all mutations are harmful. In most instances, they weaken or damage the organism so seriously that it will not long survive. If it does survive, its offspring tend to eventually die out.