As both these model-years concern the same series of Focus, there would definitely be some interchangeability. Body panels should interchange readily (provided you don't try to fit the hatchback from a five-door to the boot of a four-door) and many interior fittings would also be able to be swapped (provided the interior colour and trim materials of the two cars matched).

Mechanically, however, you need to be a bit more careful. Obviously, there would be major differences between the driveline of the diesel version and the more common petrol model, but there will likely be differences to driveshafts and all sorts of components when you compare a manual Focus to an automatic one. Different trim levels can also cause interchangeability problems in terms of a base-model car not having the electrical wiring to support the convenience equipment of the upmarket version. Things like the power windows in the rear of a Focus Ghia, for instance, will cause problems in the base-model CL which relied on manual rear windows.

For the 2010 model, Ford switched from a replaceable fuel filter located just in front of the fuel tank under the car, to a 'lifetime' filter which was part of the fuel pump. The fuel pump itself, meanwhile, is located inside the fuel tank, so that’s where the filter lives as well. Despite being a lifetime filter, contaminated fuel and other factors can require the filter to be changed and the good news is that the filter can be replaced independent of the actual fuel pump. That bad news is that the tank needs to be removed from the car to access those components, so it’s not a cheap, simple job.

It’s likely the clutches need replacing; it is a common problem with your model. Take it to a Ford dealer and ask them to approach Ford about repairing it under warranty at no cost to you. You could also approach Ford’s customer service people directly. The problem you will have in getting them to fix it for you is that the car is now seven years old and you bought it secondhand.