The suggestion of a fixed/free hub is a good one if you're unsure.

Most off-the-rack SS/FG bikes are going to come with both front and rear brakes. Track bikes won't have any brakes. You'll have options if you buy something off the rack. If you build up, there isn't anything too complicated to get what you want.

If your only concern is panic stops (a wise concern to have my friend), then a front brake is sufficient to stop you when you need to stop suddently. You say you're from road biking, so I'm assuming you're pretty good at using a front brake and modulating it for maximum stopping power.

If possible, try both before buying. Keep in mind the fixed is going to feel weird, just like clipless pedals were weird at first (and every other new thing you had to learn/adapt to).

A majority of the responses here will be FG because that's just were board opinion is.

Good luck. Post pics when you get the bike!