I moved into a two story house with a 42 inch fireplace box
Did you get the chimney inspected? If not, do you know when it was last cleaned?
I would not burn another fire until I was sure that chimney was clean. There could be creosote build-up and you could start a chimney fire.
As to the smoke, most likely negative pressure inside the house. Cold air comes down the chimney forcing smoke into the house until the chimney warms up. Crack a window until it does.