Is it fine to eat two eggs a day including the yolk? How many calories would it add?

Yes, it is. Eggs are high in protein, calcium and they contain iron. However, everything is best in moderation, so don't have them everyday. Plus, don't just consider calories, consider what the food contains. An egg could have the same number of calories as some junk food, but this doesn't necessarily mean you could substitute the egg for the other food, as the egg will contain more beneficial things for your body.