I couldn't think out a better way to show this. I think when I make them this weekend I can get Mr F to photograph each step while I do it. It was pretty hard to do it and video it at the same time. Even harder with Kid bashing into the table.
I will answer your questions if this doesn't help you out enough.
Basically make royal icing in whatever manner you'd like.
Make a thicker icing for piping an outline of your cookie shape. This will serve as a dam for your thinner "flooding" icing. Outline cookies inside of the outer edge. Let icing dry a bit. Make a looser icing. If you stick a knife in and make a dollop it should drop back down to a smooth surface (you kind of need to watch the videos to picture what I'm talking about) in 3 seconds. That is thin enough to flood while not being so thin that it is a glaze. You can either use a piping bag (and I suggest a #3 tip for the outline and a 3 or 4 for flooding) and fill your cookie in. Or you can dollop the thinner icing in the middle of the cookie and push it to the edges with the tip of a butter knife (or similar). Let your cookies dry completely before packaging!!!