Q. 1. Does it matter who blesses something? For example, is it more significant if his Holiness the Pope blesses something or if a priest does? Is one a "better blessing" than the other?
A. 1. When it comes to blessing objects, the priests (priest, Bishop, Cardinal, Pope) are all God's instruments who pass on God's grace from God to the object. What counts is obtaining the grace, not the person or the clothing that he is wearing.
All blessings are equal because they all come from God. If one blessing happens to be greater, it is because God decided to increase His blessing(s) towards one particular person because He is greatly pleased with that person. It has nothing to do with the touching of an object that was blessed.