Nothing needed except bare hook. Current will keep it off bottom and you will successfully SNAG your fish.  

Personally, I think it's your personal preference.  If you believe in it, you will catch more fish because you're fishing with more confidence.  I think that either wool or the corky gives your hook a little more drag (translates to: lift in the current).  If you do use corkies, keep them small if they're tied above the hook eyelet as it will interfere with the snagging...ooops I mean hooking action.  I've been told that the corky should be no more than 1/2 the size of the hook's curvature diameter.  If you use the tag end technique, you don't need to worry so much about the size as the corky is behind the point of the hook.  I've done it all and really can't say that  either wool or corky worked better than the other.  Small spin and glows will also do the same thing but for those I definitely would tie it to the tag end.