About eggs, i doubt that they are 3 weeks old when you buy them. But always store eggs in the fridge. You can more or less check the freshness of eggs by frying one. If eggs are fresh the egg whites has much better texture and dosnt float out on the frying pan.
I learnt a trick from a friend who used to do long cruises. They increase the lifespan/ freshness of the eggs by inverting them every few days, which moves any air bubble there, and also may mean the yolk is more likely to remain central, so less likely to break when cracked. So I turn the carton every day or so in the fridge. Although reading around, this is contentious - but can't do any harm, right.
They do say the worse thing is bringing refrigerated eggs out to room temp and the refrigerating again as condensation & moisture from warming greatly increases the chance of bacteria getting into the shell
