I find that I need heated feet more than heated hands.

Last year I experimented with putting some nichrome wire between a couple of sheets of kapton tape and hooking the whole thing to one of my 7.2 volt 4 cell (2s2p) cheap LED packs. It worked very well, it turns out you only need about 8 or 10 watts per foot to keep toasty warm even in very cold temps (below zero) wearing mountain bike shoes.

IMO, buy a cheap < $30 light for a headlight, then play around with other solutions for the gloves/feet - I would NOT want them tied together personally.

I'm with Robert C on lights - a $30 battery/LED is brighter than any dyno system on the market, and since it sounds like your commute is a bit like mine - gravel road and sometimes very rough pavement with sometimes a 10 inch wide safe path between tire-destroying potholes and cracks, you can't get away with a mediocre light.

Oh, and on the heaters, fuse that thing. It's going to be on your person. You will NOT be happy if you have copper wire running from your waist down your legs (or up your torso and out your arms) and the heating element shorts out - there's enough current to make the wires really damned hot, possibly hot enough to melt fabrics that are up against your skin. The LiIon pack will have a polyfuse in it, but it can still put out 2 or 3 amps, enough to make you really unhappy.