Answer to Q3.
The raw materials used in the manufacture of baby milks and of the final product itself must meet very strict specifications and the highest standards. The manufacturing process involves thorough heat treatment which ensures the microbiological safety of the product. Quality control procedures are very strict and stringent standards of hygiene are in force throughout. Levels of contaminants are kept to an absolute minimum complying with national and/or international recommendations. By law pesticide residues must be below 1 part per billion and are usually either absent or at levels so low they cannot be detected. Rigorous tests for shelf-life, microbiological safety, nutrient levels and suspected contaminants are carried out.
It must be realised however that infant formula powder is not, and cannot be, sterile. To make it so would probably damage some essential components. Further, water used in dilution cannot be guaranteed to be sterile.