The radio code needs to be determined by the serial code on the radio, and the code will need to be retrieved at the dealership.
The overheating problem is the most crucial, if you continue to drive the vehicle and it overheats, you can do serious damage to the engine, if it hasn't happened already. This needs to be looked at by an experienced mechanic, and without money this makes it tough. Try your network of friends and family and see if there is someone that can help, or try the local shops and see if you can make payments for work provided, or even try to work off your bill in some way.
Good Luck!