Strange Cooling problems with 2004 Tundra

I have a 2004 Tundra with 110k miles. I had the timing belt and water pump replaced about 10k ago. I have noticed that my radiator overflow tank is always empty. I fill it frequently and every now and then there will be a fair amount of coollant on the ground. Otherwise dry. Then recently I noticed the temp gauge in the red when at stoplights, then ok once moving. I quickly added a coolant to the radiator, which seemed to cure it. And then a few days later there was coolant on the ground. Then the other day I noticed that my heater wasn't working, just cold air, and then noticed that the temp gauge was in the red again. As before, I cured by adding coolant, and then again, a day or two later there were puddles under the car. Does this make any sense to anyone? Thermostat issues maybe and/or Fan clutch issues? The truck runs great, I simply need to keep an eye on the temperature guage. Thanks for any thoughts on this.