I'm not sure what to tell you about night filming, since I really have never done it, nor thought much about doing it, but for daytime use I have a Canon Elura 90 that I carry in a small tank bag. It's a great camera, but if I was buying one today I would definitely find one with LANC capability, as described above.
I also haven't run dual remote cams to the camcorder - I just mount my single cam in different positions and then splice the video using editing software. I've seen vids that show fore and aft views at the same time, and it's kind of a neat thing to see occasionally, but it gets a little old after a while, IMO.
As far as remote cams, my favorite is the Adventure Cam 3 by Viosport
(http://www.viosport.com/), which has the best image quality I've seen. Unfortunately, the audio quality is very poor. That matters to some people but not others. Their choices in accessories are second to none - every kind of wide angle lens, mounting kit, you name it.
I also have the motorcycle camera by Twenty20 (
http://www.twenty20camera.com/). The audio is better, but the video is not as good. Power is provided by direct hookup to your bike's battery.
I've also heard of others who like the Helmet Cam
(http://www.helmetcamera.com/), but I haven't tried that one.