funny, when you hit the options box from SmoothBind the last fader is for the Dropoff rate. you can´t miss it usually. maybe an installation error..?

you can´t 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 don´t use the smooth operation too much when you start painting the weights