Out of frosting
you can use green and yellow frosting to make a lime green frosting
Once it's completely cold you can start frosting! Otherwise it will make the frosting runny.
yes there is.
Use a chocolate cream cheese frosting.
Frosting is made with sugar - usually confectioners' sugar - liquid and butter. Flour is not used in making frosting.
1/4 teaspoon
yes.
All you will do is simply make a frosting (or buy some store bought frosting already made) and add a lot of green food coloring. To make homemade frosting you can find several variations of frosting recipes at www.allrecipes.com , www.foodnetwork.com , and www.recipezaar.com . A chocolate frosting might be more difficult to make green but it would probably end up as a darker color than a white frosting.
check out http://www.helium.com/items/1189518-recipes-cream-cheese-frosting it looks pretty good :)
whipped frosting
Devil's food with peanut butter frosting