Hummingbirds are territorial so the more feeders you have out the better as long as they are spread out and not within sight of one another. Great distances are not necessary, just visual barriers. Flower nectar is nothing more than sucrose and water. Therefore making your own nectar using 1 part sugar to 4 parts water is the closest way to mimic nature. If you choose to buy prepared nectar, choose one that is uncolored.
Food coloring is unnecessary in nectar.
Remember the feeder is an imitation flower. The flowers are colored, but the nectar is clear. Fill your feeder with only a small amount of nectar at first. The bird can easily reach the bottom of a feeder with its tongue. Clean the feeder every 3-5 days with hot water.