Help with my 2WD Jeep in the winter...?

The 2WD thing has nothing to do with braking, one thing people don't understand is that 4WD helps you go, but not stop. As far as your problem goes, I would first put as much weight into the back of your jeep (E.G. sandbags, free weights, any thing heavy). Next I would have your tires checked: proper inflation, baldness, rotation. Not sure what to say about your brakes, It sounds like they are catching a little harder in the rain. good luck and be careful.