How much damage have I done to my car?

That was oil vapor, not smoke, and that is normal in a hot engine, but especially if the level is down a quart or two or more. Engine oil helps absorb some heat out of the engine to the sump. If you're really worried, use engine flush before changing the oil, to remove varnish and sludge that may have built up. The car will likely not have been damaged, unless it ran low enough onoil to make the warning light come on.

You might as well think positive. Was the car running OK, no problems? You say it was "smoking", but if it was hot, all cars will do that, a little bit.

I believe in this case, if there was something wrong, it would have gone wrong already. If there isn't, you certainly won't cause any damage by changing the oil.

It's not so much of an issue if you've been easy on the car, though turbochargers do like clean, plentiful oil. In any case, it's not going to be worth unbolting anything to look for damage. Carry on, lesson learned.

The only way to know for sure is to do an engine tear-down. But, as Erik already pointed out, if the vehicle is still running okay, you're probably still okay.

But, in the future, turbocharged engines like fresh, high quality oil. The easiest way to get the engine to last a long time is to always do oil changes on time.

You have added an infinitesimal amount of extra wear. So no worries. You are wise to have it changed asap. If you want your car to last longer ask for fully synthetic oil as this protects much better than standard oil. Smoke when you open the oil filler cap on a hot engine is normal. Also you look far too good to throw to the hounds.

I'm going to throw you to the hounds for not checking your oil regularly. That was an epic fail. If it was smoking because it was nearly out of oil you have probably heavily increased the wear on your engine that was already happening by running it so long on dirty oil. Oil starvation and dirty oil are particularly bad for turbochargers.

9000 miles over what? the manufacturers recommended interval as stated in your owners manual? Stop relying on others. Read the manual. learn how to check the fluid levels and pay attention to when they need attention

Only time will tell. You should have a mechanic look at it so trained eyes tell if anything else is wrong.

My guess is repairable damage, but not cheaply.

9000 miles over is over. Nothing you can do about it now. The damage is done. The car still runs so that is good for you. It will not heal itself. You just aged the engine faster than one who changes his oil when he is recommended to - but again hardly measurable by you. It is what it is now. It won't get worse...faster because now you changed the oil which is dirty.

I have seen some vehicles go 50,000 miles and they never changed the oil, they just made sure it had sufficient oil everytime they took the vehicle out,by pulling the dipstick and adding when it was low...as now it is slowly burning the oil. All engines do, this one is burning more sooner.
. Everything is repairable. But it is not severe enough to warrant worrying about it now. Maybe the next owner will.
Having a turbo means parts are spinning around even faster at high speed so high speed means it should spin in clean oil....not in a grinding solution.

I would not worry about it. I have possible pregnant girls to worry about because I fork around alot....and my beer is getting warm.