Driving every day, you should have no problems running 2 B1W's like this. Regardless of which cam(s) you choose it will shorten the life of your car battery some, but most likely not to a degree which makes the idea unsound. End costs will probably less than $0.50 per day, which to me is a good deal for the protection you get.
The 0906 might have better vid quality in front during daytime, but it's never been as reliable and trouble-free as the B1W is, and that has become even more true with the QC apparently dropping on the 0906 in the last couple years. It does have the advantage of an easier install and less bother to retrieve the rear cam's recordings since the cam in front will have them both. That much goes for any 2-channel cam.
As for powering 2 single cams, as long as the chosen fuse or circuit has enough capacity to handle a couple extra amps, you can tap both HWK's into one place, and most circuits rated 15A or more should be able to do that for you. I think that would be preferable if possible so that if there is a problem, you'll know exactly where it is.
Phil
I'm really not an electric guy and would probably like to stick each HWK into a different fuse rather than putting both HWK's into one fuse