I have some problem with the appearance of the lines. I tried to change it in the Styles window, but I wonder if it is adjustable anyway. The lines appear more like zig-zag lines, which makes it a bit unattractive . Is there a way to make them more look like a straight line?
this is an anti-aliasing artifact. Try going into the SketchUp > Preferences (Mac OS X).
In the window that opens up go to the OpenGL and increase the Multisample anti-aliasing.