Which dev path should I take.

Just asking a quick question for the best set up. I spawned in a region with 1 rich iron deposit and good fertility. Should I get charcoal then deep mining, or heavy plow then bakeries. Also another quick question, but how do I make it so multiple people can work the same field with an ox, since for some reason only one can work on it at a time which is kind of stupid. Also does twice the efficiency mean it makes bread twice as fast or twice as much.