1. There are a few ways you can have an icon and button synced, but buttons themselves do not have an option to have icons. You could either group the two, place them both into a container, or you could use Fill Image that has an image of an icon. If you use Fill Image, you would need to make an image exactly how you would want to the button to appear, as filling it will fill the entire button.
2. Since you used a container, you would want to have two icons, one for the default color and one for the hover color. Set the icon with the hover color to a state so that it is only visible when the container is hovered over. You would use the "On Hover" for the container to set the state. This will simulate the icon changing color when the "button" is hovered over.
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