1992 Toyota Camry

Hi. Have had a Toyota Camry for 5 years, with no problems. One day I was in a drive through and the thermostat starts to rise rather rapidly. Was stuck in drive -thru with nowhere to go, and then I noticed a small amount of smoke coming from the hood so I immediately shut the car off. Eventually I had to turn it back on due to being in a drive-thru and the car had cooled itself off to a reasonable degree. As I was driving the car home immediately after it stayed cool but when I was idle it would rise again. When I got home my husband checked the water tank and the water was bone dry so he filled it up. The next day I drove around for 2 hours tops doing errands with no huge rises in the temperature, when I got home my husband checked on the car again and noticed the tank was completely dry again. He filled it up and let it sit overnight, the next morning the tank was still full so we came to the conclusion that it is only leaking (if it is idle and running it leaks from the front passenger part of car) when it is running. Asked around and most people automatically go with the blown head gasket theory and/or a cracked hose but we don't see a milky type look or texture to the oil and nothing leaks from the radiator when it is turned on. Also noticed that right around the same time this was all happening the A/C now no longer gets cold. Would love any type of diagnosis you could offer with what info I have provided. We are selling the car since we purchased a new car and would really like to be as honest with people as possible about what is going on with it. Thanks.