That's pretty cheap... I'm tempted to grab one just to see how poorly it really functions. It doesn't appear to have the cojones to roast coffee, but I bet it would work for okay for garlic... If I try it out I could add it to the list of other crappy roasters I regularly disparage...
As for cooling, with any roaster I am going to remove the beans immediately and cool them externally so the cool-down time is not dependent on cooling the roaster as well. Of course I'd be running any recommended cooling cycle on the roaster, but without the beans present.