Depth-of-field rendering in lightwave is easy. You need to select the camera, then go to the camera menu. Make sure anti-aliasing is on medium or higher, then select the depth-of-field button. Click focal distance (the distance at which objects will be fully in focus) and alter that as appropriate. There's an option to visually show the focal distance, but I've lost it ^_^ Just use trial and error until you find the correct focal distance to use for each render.
As for f-stop... On cameras you get a longer depth of field with a higher f-stop setting, and a smaller with a lower. It's to do with the size of the lens - higher f-stops make the lens smaller. Anyway, as far as you're concerned, if you want a larger area to be in focus either side of your focal distance, you'd lower the f-stop. That works inversely as well.
As for that procedural background in the second render, lower the contrast and 'small power'. That should make the edges less sharp. Procedurals are fun - just remember to play around with the rotation and scale settings so it doesn't look the same all the time.
