foot retention is only important if you run brakeless. Well, it's only vitally important, if you have brakes and you slip off, you can still stop yourself without using your emergency pedestrian brake. It's nice to have some kind of foot retention, just to help you even out your spin, but you don't need it.
When you first put on the clips and straps, run it as a single speed (Not fixed) for a while, just until you get good, and I mean really good, at getting in, it's much harder on a fixed, so your likely going to need practice.