Okay, if you can get the fan motor started with a screwdriver, then I definitely think the capacitor is the main fan problem. Compressor sounds just like a refrigerator, its just the sound a running compressor makes.
Now, if you got fan running, and compressor is running, and still not cooling, you have other issues. Is condenser coil clean, very clean? If so, feel the large line(there are two lines going from condenser to coil in furnace, one is large one is small) and tell me if its cold. If its not cold, you most likely have a low charge of refrigerant, in which case you would have to call in a licensed tech to service unit. I'm betting you need to clean your outside condenser coils. First get that new capacitor, then when unit is running normally, spray water on the condenser coil, let me know if it cools then.