I commute 21 mile rt. 5 days last week, 3 days this week (thanks to a broke spoke). Usually one side of the ride is in the dark. The more lights you can get on the bike the better off you will be. I have a small one on the back of my helmet, one on my trunk/pannier and one one the trunk rack. Odds of all three batteries going dead at the same time are slim. I ride the shoulder as much as I can, but if I take the road, I will be at least 4 ft from the white line. Otherwise people want to ride to close. All of mine is on a rural route. I have 3 stop lights and 2 stop signs in 10.5 miles. Be careful of how much you carrier. My spokes are starting to go and the rear wheel bearings are going out. 1300 miles on it. If you carrier more than 15-20 lbs look into getting a front rack or something to even out the weight.
I love commuting, You will require a little more sleep but you will start looking foward to your commutes
Brian