Used Cars: what to look forward to, mercury grand marquis, brand new cars

Question
I recently bought a 1999 Mercury Grand Marquis GS with a mileage of 40,144 this is the main reason that I bought this vehicle.  I bought this car from a good named dealership, but when it was to to pick this car up, since they had not been able to service it yet so wait at least a day to inspect the car.  Upon inspection they found that a window motor was going out and they fixed it with no problem.  When I finally picked up the car and drove it for a while I noticed that the when you briefly take your hands off the wheel it drifts to the right and the steering wheel is slightly off centered, I took it in and they fixed the best that they could, it does not drift but the wheel is very slight off centered so I decided to leave it this way.
here is the questions that I have.
Is it normal that the windows go up very slowly ?
At start up why does it sound like its at high idle?
What problems can I expect with this vehicle?
I ask this last question because I am used to brand new cars but due to finical problems I had to go used and bought this one for the price of $6,600
I understand over all this is a good car is this true:

Answer
Ok... To start, all cars will drift to the right on most roads, most roads are angled such to allow water to run off and in the even of a driver releasing the wheel the car is less likely to run into the on-coming traffic... so if you reall want to know if the steering is off you will have to let it go in a parking lot you know is flat, or on the opposite lane of a deserted road... the high idle is normal under many conditions (if its cold it helps) and as long as it settles shortly its nothing strange... the windows go slow probably because the motors are old and will go out eventually... they say they fixed it but you cant be sure, and the model car might just have slow windows... so I cannot really say... problems will be the same as any other car.. as old as it is you will probably be replacing some of the simple components (starter, alternator) and look for the electronics.. (power seats, windows, locks) to probably go out as well... all these things are due to age, the low miles means the engine should be alright for a while...  It's a decent car, not a great, but decent car... 90's domestic cars werent of the best quality and were much lower quality than the imports of the same years.. (domestics have since become alot better, and while many are still lower quality, they are substantial improvements over the past)... If I missed anything just ask again, but I think thats everything.. to help with the windows, if the fixed one is alot faster than the rest - the rest will die eventually... otherwise they may just be slow motors in general and everything is fine... hard to tell... thanks for writing!