if i cover a cake in regular fondant and i want to paint a logo / picture onto it what will be the best medium......is there a particular type of decorating paint or could i use food color paste????
You can paint on fondant with paste colors, or paste colors thinned with vodka (for a less intense color and faster drying time).
If your logo is really complex, it might be easier to see if a bakery in your area will print an edible image sheet for you. They usually don't charge too much to do it.