One chunk should be enough...certainly no more than two. Three will be too many in my opinion.
A couple semi-related thoughts (only my thoughts...not meant to offend anyone)...
- I season the skin because I eat the skin. The skin is about the only reason I eat chicken. I also don't use "rub" on chicken as I don't like the flavors I tend to get. I season, but very simply.
- Soaking your wood chunks does no good. If it makes you comfortable, then continue to do it. Just realize that you get no benefit from it. Sometimes the placebo effect can be a good thing.