you need to pull the codes and see why the light is on. After you figure this out I would figure out where the oil smell is coming from. Pretty common sense stuff, Is smoke coming out of the tail pipe? Is the engine leaking oil? dripping on the exhaust? You will find it.
The burning oil smell is most likely from a valve cover oil leak, and oil is getting on the exhaust. It doesn't take much oil to make a big stink. It could also be the oil pan leaking onto the exhaust under the engine, so verify if you have oil around the valve cover or the exhaust under the car.
Find a code scanner and have your codes scanned. This used to be free at auto parts stores, but now they want us to pay because, I suppose, the makers of the code scanners were upset. A cheap scanner is a good investment if you plan on working on your own vehicle, or any vehicle in the future that is OBD2. Those scanners will work on any make or model after 97 or so. Now, once you get the codes, write down the number and bring it back to this site. Look on the thread list page here in Technical Chat, and click on the link that says "Ford Focus Technical Chat Stickied threads", then look for the link to "DTC Codes and their meanings". Go to that page, and look for the number. Remember, DTC codes are only a guide for repairing vehicles. Just because you have a code that indicates it might be an oxygen sensor, for example, doesn't mean it's not a bad injector or loose vacuum line. There is still detective work and diagnosis to be done for a proper repair the first time.