The mark of the Designer is in the design of the elementary particle physics that could be used to build a molecule like DNA. The fact that the elementary particles could even come together in such a way is support for a Designer.
Of course if things came together in some other way that would also be support for a designer. There is no way in which things could come together that could not be construed as support for a designer.
Hardly. All it needs is a little help from the second law of thermodynamics and a bit of applied energy.
Did you have even a basic course in chemistry, molecular biology or organic chemistry, and physics?
If so, you would understand that the essential governing forces, bond formation, secondary and tertiary structure of compounds naturally resulted in the shape and structure of DNA.