My coolant level drops after a week, and when sitting in traffic it almost over heats until I move again. No idea if its leaking somewhere or evaporating. Also no heat in the winter and smell coolant when fan on.

I'd suspect the pressurized coolant cap first. If it's loose or doesn't seal well then you might get symptoms like you described. A new cap should be under $10 and any local parts store. After that, I'd look into replacing the thermostat and checking your coolant reservoir for any signs of oil mixing in.

You may have a small leak in the heater core. The fluid would collect up and then drain through the A/C drain onto the ground. You may only see this when the vehicle is running. Top up the fluid and run the car up to temperature. Have a good look throughout the motor. Put a piece of cardboard under the car if you cannot find anything. This may take a good 20 minutes or so just be patient.

Can I do the thermostat myself or do I need to see my local mechanic, also already changed the coolant cap already cause it wasn't sealing properly.

You should be able to do it on your own. Look it up on Google for your make model and year. Or in a Chilton manual if you can get your hands on the one for your model yr. Some libraries have them.

Sounds like thermostat issues i had the same prob with my ga.