Yes, they are usually the same as fed to birds, just be sure if you buy from the bird department the label lists only black-oil sunflower seeds as ingredients; some companies add a product called Bird-Kote (may be spelled different) which is a vit/min for birds.
Yes, feed shells and all; and typically a 1/4 cup or less is sufficient to add shine to the coat without adding too much weight. [bOSS is very high in fat, thus calories, which is why its good for the coat.]