I use about 4–6 grated potatoes, 2 eggs, salt, minced onion and a ½ c. flour. The main trick is to eat them as soon as they are fried, not to let them sit too long. Delish!
Schmaltz is rendered chicken fat. It’s often used in Jewish cooking because of the kashruth proscription of cooking or eating dairy and meat together. I always cook the latkes in vegetable oil, never thought of using schmaltz for that.