Higher resolutions mean that there more pixels per inch (PPI), resulting in more pixel information and creating a high-quality, crisp image. Images with lower resolutions have fewer pixels, and if those few pixels are too large (usually when an image is stretched), they can become visible.
This is incorrect. Gouache painting is very very similar to watercolours, so much so that the two can be used together. It is an opaque method of painting.
