Do you add hot or cold water to boiling water?!

That isn't actually true. Hot water does boil faster then cold water. But when you get hot water, its water that's been sitting in your hot water tank and isn't too fresh. Cold water is constantly flowing and usually tastes better. This is the whole reason why this statement was created.
To answer your question, if its for tea or a something you are going to eat/drink, use cold. If you are just boiling water for cooking or other purposes, hot water is fine.

It doesn't matter, but hot water will allow the water to boil again faster. And cold water doesn't boil faster than hot water. Whatever gave you that idea?

I would add hot water so you do not cool down the boiling process.

allrecipes.com or www.food.com

Good question...I don't know the answer. I would just put warm water I guess..

hot

doesnt matter