I have a Bosch VSO (variable speed, orbital) electric soft start sander that I really like, and it has three differant hook&loop pads, stiff, medium, and soft. I tried all the pads when I was stripping when I did my jeep (I hooked the sander up to vacuum and used a face mask), and I used the soft pads between filler and primer and it worked pretty well but you should use blocks or a long inline sander when doing the rough sanding on filler to keep the contours flat.
It is a bit dangerous to use an electric sander when you are sanding new paint due to the fumes, and you shouldn't use it to wet sand at all. Make sure you plug it into a GFI.
As with any sander you should always keep it moving and stop and start it while it is in contact with the surface