When you stop taking ripped fuel you'll have one HELL of a headache. Definely ramp your intake down for around a week. Take a one pill serving twice a day for a few days, then one pill a day or two and then a few cups of tea for the next few. I have been pretty hungover from immediatly stopping caffeine usage, and know a guy who had to go to the hospital after stopping HEAVY use for three years of law school. I would hypothesize it comes from a drop in blood pressure after all your blood vessels vasodialate.
You shouldn't lose any of the weight, your metabolism might get a bit slower for a few days, but overall it should go back to where you were when you started. With (hopefully) better eating habits of smaller meals, since caffeine is a appetite suppressant, you should keep it all off.