Ctfortner, I'll answer the easy question first. Although I've never run it until it was empty, it is suppose to run for 7 hours when it running wide open or a lot longer if the Eco-Throttle is on.
Now to noise... At seven feet away the noise level is 49 dB with the Eco-Throttle and 59 dB at its rated load. Putting that it perspective, a converstation is about 55 dB, your TV at home is 60dB, a lawnmover 92 dB and a circular saw 115 dB.
Unfortunately noise is relative especially in different environments. I have no problems running the generator while I'm camping by myself. However, while I don't have a problem warning up my Hummer engine or running my AC, I would not think of running the generator at a camp ground even during the day just becasue it is a "generator".... Hummm I probably need to compare noise levels and see it there is a big difference or is it just my perception.
Ruide