Q.Watering the polka dot plant
How often do I water it and how much?

Certified GKH Gardening Expert
You will want to water when the soil is dry down to about an inch. This will take a different length of time depending on conditions around the plant, so it is best to just feel it to know when it is time to water.
Water until it starts to run out of the drainage holes, and allow all extra water to leave the container and saucer. It should never be allowed to stand in water.
Here is an article that will help you to grow these plants: https://www.gardeningknowhow.com/houseplants/polka-dot-plant/growing-polka-dot-plants.htm