Yes, you can. Be prepared to take many before you get a good one!
Just point the lens through the viewer. It helps if you have a macro setting on your camera, since it's closer range than most non-macro modes can handle.
Possibly. You need a camera with a decent macro function. Otherwise you won't be able to take anything that close up. You better have a digital camera, or a lot of money to spend on film.
Finally you need patience, and maybe a helper. I needed to add extra light to the scene in order to take the picture without a flash, and adjusting the camera, lights and scope at once was very difficult.
The hardest part is getting the right angle. I found that if you were a degree or two off, the hearts and arrows wouldn't look right. At first I thought that I didn't actually have a true hearts and arrows diamond the way these pictures looked... but once I would get a shot at a centered angle, it formed a perfect H&A pattern.