A fender for your front wheel will keep your feet a lot more dry.

Thin layer glove + dishwashing gloves. The dishwashing gloves are pretty much windproof, and the layer keeps you warmer. Go for a size bigger than usual on the dishwashing gloves. (Plus, your hand signals will be very clear.)

Wool is good. I have a thin wool cap that fits under my helmet. It keeps my feet warmer. (No joke.)

A good-quality rain jacket is nice. Does not have to be cycling-specific, although that helps.

If it's really POURING I wear rain pants and gum boots with thick wool socks. Not very comfortable, but keeps my feet dry.

If it's really COLD I wear my winter boots, those that are designed for Montreal winters. I don't think you'll ever need that in Austin.