A. Don't worry about the calories. Don't count them and try not to think about them at all.
B. No set amount of protein, especially when just getting started. Eat real food, any meats/fish/poultry you are hungry for along with some low-carb veg, and then eat again when you get hungry again.

It is an adjustment for most of us to learn to pay attention to hunger as our signal to eat, rather than the clock or social norms. But it is so healthy to do so! Eat when you're hungry, stop when you're no longer hungry. As long as the food is real and LC, your hunger is your best guide to timing/quantities to eat.