To even up the width of fondant ribbons after they've been applied, start by cutting them a little wider than you want them to be when they finish. For example, if you want a 1" ribbon, cut them to be about 1 1/4" wide.
If the color of the fondant has bled onto the icing underneath you can scrape it off using a spatula. If the icing softens up too much and the color is smearing you should put the cake back in the fridge until it hardens up again before doing this.
Kara Buntin owns A Cake To Remember LLC, custom wedding cakes in Richmond VA