With an automatic you'll need to do a lot more DWL and less P&G. Do all you can to keep it from downshifting on hills. Lose speed as you climb, but if you lose too much it'll downshift. To solve that you need a running start for the climb so you can lose speed and still be above the shifting point.
In town, anticipate everything as far ahead as possible. Stops are even harder on mpg with an automatic, so avoid them like the plague. Even 5 mph is better than a full stop.
Yeah, the problem with cold is it slows down the chemical reactions and reduces the power the battery can put out. Heat really kills them, but they're ok until the cold weather shows the weakness. I got this chart from Interstate a while back.
