Welcome to CC!
Your wayyyy over my knowledge, but I hope someone who knows will come along soon 
It all depends on the look you are going for. If you want a more 3D, lifelike look, I would go with a hand sculpted fondant rooster. Anytime I model something, I add tylose powder to my fondant to help it dry out better and to avoid any potential problems with cracking or breaking. An easy way I have found for doing things is to use a cookie cutter to cut fondant into the shape you want and then paint it or use an edible transfer sheet. You can see in my gallery where I have done this. HTH!
i dont care for modeling, because i find that it is difficult to get the detailing in before it droops or cracks or falls...but in my experience, the exterior of gumpaste dries very quick (easy to get wrinkles), and fondant dries very slow. how much time do you have for this? i have seen the advice to mix half gumpaste and half fondant which makes a lot of sense. if you are working with gumpaste only and it is flat...you should be fine to do it a couple of days in advance, but for thicker pieces, you should do it oneweek early to allow drying time all the way through. for a figure made of just fondant, give yourself a week at least for it to dry thouroughly as well. you may want to try using gumpaste flower or leaf cutters and veining tools to get the feather effects. i would recommend painting with dry luster and petal dusts so you get a nice shading....do that after it has completely dried.
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