Is a 2011 Ford Fusion a good car?

I turned 17 about a month ago and we're ready to buy a car and get it one soon as possible. We're looking for a sort-of new, midsize family sedan. This will not only be my car to use, but for the whole family, when our truck and SUV are not neccesary. However, we want to pay 10k or less.
We went to a local dealership and found a 2011 Ford Fusion SE with the 2.5. It has 64k miles on it, but was a one-owner, commercial vehicle, meaning it was well cared for. The clean Carfax shows all the records and history. The salesman was very nice and honest unlike some of the others we went to. I have experience with the Fusion Hybrid because my friend has one and that is a good car, so I know that the Fusion seems like a good car in general. But, although we're ready to make the purchase, I would like a few opinions on specific things to look out for on Fusions and if we're making the right choice.

Throttle control/transmission light?

I have a 2006 Ford Fusion. We just changed the valve cover gasket and spark plugs. We started my car and it took a while to start up and doesn't sound right at all. It almost seems like it's going to shut off as I left it running. I have the wrench light and check engine light on now. The wrenk light says throttle control/transmission and says it illuminates when a power train fault has been detected to take it to a dealer as soon as possible. Did we do something wrong when we changed the valve gasket cover and plugs?

Stuck Clutch - Piston not returning to rest?

I left my car outside overnight on Tuesday and when I got up I had some troubles getting moving. I wasn't sure what was happening but it turned out to be the parking brake being stuck due to the cold. I drove about a block and turned around when I realized the brake wasn't going to unlock. About five houses down from me the car stopped moving. The engine was redlining but no movement whatsoever. Essentially no power going to the drive train even though the car was in gear. Couldn't go forward in first or back in reverse. After the outside temperature warmed up the parking brake unfroze and is now working fine. Unfortunately there's still no power going to the drivetrain. The clutch depresses but feels like there's minimal upward pressure when I take my foot off of it. With the car running and without the clutch engaged I can shift into all gears. The same as if I had my foot on the clutch. I believe there's a piston that the clutch pedal pushes against that is stuck and not returning to its resting position. Before I climb under the car and start hitting things with a hammer I was wondering if anyone has an alternate diagnosis. If my diagnosis is okay I'd appreciate links to some pictures or diagrams of where that piston is located on a 2006 Ford Fusion with the 4 cylinder engine.

Humming Noise coming from under the hood. Any ideas?

I have a 2008 Ford Fusion SE 4 Cylinder with 78,000 miles on it. When I accelerate I hear a humming noise coming from the front. The higher the RPM's the louder it gets. The sound begins after 1000 RPM's. I sat it and parked it and put my foot on the gas pedal and went up to 4,000 RPMS and it sounded like a siren you would hear in the movies for like code red or something I don't know. I have no idea what it may be. Answers would be very much appropriated.