As long as they are dead wood [seasoned, dry..] I see no reason why not .. I just cut down a huge Walnut tree and am already useing athe limbs that were damaged a few years ago in an ice storm.They were already dry. Hemi..
Not unless it dead and dried out. I don't think you can or should use wet apple wood. I'm not sure why but I have always heard that you need to use dried wood. Now the wet/green wood will create sap and other bad things now I'm not sure if it would do anything to the taste of the meat.