Hook: there are lots of variations on the guard rails, as well. The spacing from the running rails varies, but it's never as close as the check rails in a switch. I've seen it made with anlgle iron. The ends vary as well. Some just bend down into the ballast; most bend inwards; some bend in to meet and have a little point casting there. I think most probably bend down so that they don't snag anything dragging.
I have to add some to a stretch of track -- I plan to drill holes in every 5th or 6th tie and put in spikes. I'll be using some lighter rail tham the main track.