It opens at 6am. But hot food (waffles, breakfast sandwiches, etc.) might not be available until 7am. Before that, it's yogurt, bagels, muffins, anything that's already prepared. I think breakfast service ends at 11am.
I am not sure about the hours they are open, but the last 2 trips we ate there, there were no Mickey waffles. They were regular rectangular waffles. They still tasted good but if your heart is set on Mickey waffles, be forewarned that they may not have them...