Hi Phil....welcome to the SI family. I have three smokes under my belt with chicken. I can tell you that my family absolutely loves the smoked chicken. Not to mention there are endless amount of recipes for the left overs.
Smoke time in the 3D is roughly 3 hours. With regards to placement I like putting birds as high as possible and bigger bird over the the hottest part of the element.
Just a side note I follow the lazy Q recipe to a tee. It is fool proof
Good luck
Court