If you go to Profile>>Use Large Display Mode - that will change the font, but I don't think there is any way specifically to change the font type or size.
To add color to a dashboard you have to set thresholds that tell that color to appear. In the component of a dashboard, say a scorecard, you have to be in edit mode. Select the component you with to change and select the Alert Rules tab.
Here you can set color thresholds based on the value...
When the scorecard hits any of the specified values the dashboard will change color.
Brilliant, thank you for your help cmajewsk!