I think I might have an engine problem... :(

The soot on the floor is normal at this time of year. Especially if the choke is not set right, or, if no choke, you have to babysit the engine with numerous throttle blips. What can happen is the extra fuel and soot condenses in the cold mufflers, and the throttle-blips pick it up and blow it out the back. This mixture forms hydrochloric acid in your muffler and will rot it out. I drill a 1/8 hole in the lowest part of the muffler and let it leak out. Yeah it makes a mess, but my Dynomaxers are 18 years old and counting.
The white smoke may also be normal,especially if the humidity is high.Water and energy are the normal products of the internal combustion engine. As the exhaust system heats up, the moisture turns from visible to invisible. It's still there you just can't see it. Some may condense at the end of the pipe as it hits the cold atmosphere and you'll see it dripping there. On some cars the moisture condenses back into water inside the last foot of pipe, and when you see them take off, they leave a trail of water. If you are concerned, a pressure test should find a bad headgasket.
Cold atmosphere means cold relative to the heat in the exhaust gasses, not relative to what the thermometer is saying. You gotta remember, the gasses are leaving the chamber at maybe 550 or more, at idle.
I think I would consider driving away a little sooner. If she don't like it, give her more timing. You do have a Vcan hooked up right? lol. This is the time she wants those extra 15/20*.