Protein Powder

I usually do about 5kg a day but sometimes more depending on the workout.

>>42238298
>How long does (whey) protein last?
Like all things that come in a container it will last as long as it takes to use all of the powder inside of the container.
>What are the optimum conditions for storing it? Cool and dry?
You are going to consume it for its nutritional value, the same way you consume all of your food. If you keep your food cool and dry then do that, if you store your food in a smoke hut then do that, but protein powder probably isn't very good when smoked.

>How much can I safely take at once?
Search the US Food and Drug Administration's website for a protein calculator. It will ask you a series of questions and then calculate your protein requirement based on your answers. Be honest or you might end up using more than you should and that can lead to severe liver and kidney toxification.

>I'm relatively DYEL, so I think 2-4 scoop servings, twice a day should be okay for me.
Like I warned, it isn't safe to buy any drug or supplement and then just take a wild guess as to how much you should take. Overdose is real, just look at the opioid crisis that's going on.