Is It Kosher? M&Ms sold in the United States are certified kosher dairy by the Orthodox Union, so the bag carries an OU-D. M&Ms made for the UK and much of Europe are a different story: they are not kosher certified, and the red coating often uses carmine (E120), an insect-derived dye. The country on the back of the bag matters more than the brand on the front.
Is It Kosher? Cheese is kosher when it is made with kosher rennet and produced under rabbinic supervision, which is why the symbol on the label matters more than the ingredient list. Milk is kosher, but the rennet that sets the curd is where the real question lives. Here is how I check a cheese before it goes in my cart.
Certifications Chalav Yisrael is dairy watched by an observant Jew from the moment of milking. Chalav Stam is commercial milk produced under government supervision without that presence. Which one you keep is a matter of community custom and your own rav, not a line between kosher and not kosher.