Apple and cherry go really well with duck ... I'd avoid hickory with this one. Is this a whole duck, duck breasts, etc.? If whole, are you butchering it or smoking whole?
With duck breast, that fat layer needs plenty of help (and time) to get it to render properly so it depends on how your final product will be (duck pastrami, sliced and served, etc.). If it's a whole duck I'd do it like beer can chicken ... perhaps a fruit beer like Abita Purple Haze or Woodchuck Cider, set the temp to 210 or so and let it do it's thing.
Skin won't be crispy so a trip under the broiler will be wise, whether butchered or whole. Even sliced breast would benefit from a high heat saute in a non-stick pan, I'd think.