alcohol will denature protein (read: cook). I suggest boiling it first to drive off the alcohol and concentrate some of the flavor.
If I'm trying to add a flavor to my profile, I always take a step back and decide where in my protocol that flavor will work best. Generally, I like to avoid adding flavors in early in the process due to the fact that heat tends to destroys certain flavors. I'd think I'd work a whiskey flavor in a sauce or glaze.
As for the mustard, IMO skip it. It may help rub stick but I find it makes a major mess when it comes time to transfer the meat to the wsm. And mustard is a flavor that gets killed by heat, so it doesn't add anything flavor-wise.
For helping rub stick, follow Kevin's protocol of omitting salt from your rub. Salt first, allow moisture to come to the surface and add your rub over that.