How can I extract more heat from my enclosed wood stove?
You should definitely run it with the flue open, all that smoke/CO needs to go outside, not in the house. You mentioned two vents on the bottom. Those are likely there to allow you to close the front and allow the fire to still get air. As SqlACID mentioned, spending $100 or so on a reputable chimney sweep to come take a look at it in person would be a good idea; they would be able to help you use it to its best advantage.

I would experiment with closing the front and see what effect it has on the burning rate as well as the heat produced. It is also a good idea to try to move the warmth produced by the stove into the rest of the house, so running a fan to pull that warm air away might also be something to try. 

What make/model of stove do you have? I might try googling the make/model to see what comes up on how to best use it.