Most fixed gear riders prefer just the front brake since that's where most of the stopping power is. The rear brake is their legs.

I prefer the bullhorns although the risers were fun as well, but on long rides, the lack of hand positions was annoying. The drops were good for getting down out of the winter wind, but I only put them on because they're really narrow and I wanted to see if I liked the narrow bars before I bought new bullhorns. I went from 46 cm to 40 cm bullhorns and the drops were 38 cm.