I'm a beginner just like you. bought C3 with twin lens back in February, i wasn't aware of 5N at that time....i was looking for entry level non PnS camera.  I was checking out Panasonic GF3 and NEX C3.  From my point of view, if we are beginner, and dunno much about lens, kit lens 18-55mm is good enough.  I would go for 5N if the price is only a slight different.  Well, if you have look into different lens, and would like to have the wide angle pencake lens 16mm then I would probably go for C3 twin lens.  FYI, 5N has touch screen and we can add remote shutter control device.

Now with F3, the newer model...I'm not sure what I will choose if I'm you now....F3 has added self-portrait, auto portrait framing and some cool features.  The physical outlook look quite similar to NEX 7.  You probably have to go to shop and try it out to find out what you like.  F3 has twin lens package, as well as the SEL50F18 option as well.