I knew both ways, which seems like I'm one the few who tried... :-)

You can also put a Widget manually in /Library/Widgets and just douleclick it. That opens Dashboard and adds the Widget. This is very nice because otherwise Dashboard needs some time or even a logout to "see" that I added a Widget manually into this directory. Well, I just could kill the Dock-process but hey.... :-)

When I add a widget, I just click the "1 of 2" button a couple times and the new widget has always appeared when I get back to the right page. Have you tried that?

On the Expose topic, I use it every time I switch to a window thats covered up (which is pretty often since I use Safari in a full screen window). I use the "Window Switch" button on my MX700, but if I had to reach for the F keys all the time, I'm not sure I'd use it nearly as much.