My Panasonic bread machine consumes 505-550 Watts. My oven is around 3500Watts. I use the rapid bake setting because I use bread improver. So I get a loaf in 1hour 55 minutes. I think the machine has to be more economical under these circumstances.
As regards freshness of flour, I buy wheat which I grind. My 20kg order of wheat lasts about a year and I mill it at about a kilo a time. The wheat keeps well in an airtight container, but I wouldn't want to keep ground flour for too long. I used a bag of flour I had in storage for about 4 months in France and it wasn't so good.
Jen