It sounds like you have ice buildup in the ductwork or on the little fan that circulates air.
Unplug your appliance for 24 hours and give it another try. If you still have the same problem, replace the fan.
Well, you need to get the parts fixed as soon as possible. If the fridge side doesn't work you have to fix the cooling fan inside it. Maybe adjust the temperature and see what is happening. If you don't want to buy a new fridge, use your existing warranty and replace the parts.
Because you have somethings that work and somethings that don't then there has to be something unique to the freezer that is causing the problem. I would look at the refrigerant line and the motor that serves the freezer to see if these are operational. Check the fan too.
Yeah you can fix it. It sounds like you have a bad thermostat or a bad coil. Check all the coils and make sure they are all working. Then check the thermostat and if it is not working you should replace it.
Call your local plumbing and heating professionals and have them check it it could be the compressor on the refrigerator side of the unit that is not working up to standards and if you have a warranty on it they wont charge you anything for coming out and running a dignostics on it.