The label says 4 ounces (which might be the entire bottle) per gallon of water. They reduce the recommendation as they get older. So your 1L waterer would be around 1 ounce of nutridrench.
I use vitamins and electrolytes for about 24-48 hours in the water. Some people have strong opinions on both sides of that decision. The people who just give normal water usually do it because they think the salts in the electrolytes are too much/too soon and that the benefits of the vitamins...
Hard to calculate since they will waste more or less of it depending on your feeder.
I started with 25 chicks born February 26th, got down to my current 10 chicks within a week of birth. They are now almost 3.5 weeks old. I am probably about.....30 pounds in. Most of the way thru my first...