Brisket Smoking - Rest Time
You want to be careful with food safety. The "danger zone" is generally cited between 40°-140°F, and you don't want your meat in this zone for longer than one hour if about 90° or two hours if between 40°-90·. You should start your timer when you think it reached this temperature. Wrapped in foil in a cooler it probably took some time to cool down to 140, and also it's not exposed directly to new sources of bacteria (though there will always be some that cooking did not kill, and they will start to propagate). 

Did you take a read of the temperature once you woke up from your nap? That would be useful info. I don't want to advise you on whether it's safe to eat because I don't know enough about your specifics and in any case you'll be taking a risk, but there are mitigating factors in your case which could ameliorate the risk. 

In answer to your second question, if you feel the food is safe, eat it right away. Any other course will increase your risk. Cooling it will continue to grow bacteria, and bacteria can release toxins which are harmful, so reheating it may kill the bacteria but not these toxins.