funny, when you hit the options box from SmoothBind the last fader is for the Dropoff rate. you canīt miss it usually. maybe an installation error..?
you canīt do wrong too much in the beginning with smoothBind. I myself prefere to select only those joints I need (like skipping all Joints from the end of chains to improve performance) and change Bind To: Joint Hierarchy.
max influence is good at 3 for starting. you also might check: Maintain max influence.
test the settings. you will get it soon! and donīt use the smooth operation too much when you start painting the weights
everything starts and ends in the right place at the right time.