I need help buying diapers! Experienced moms- please help?

We’re expecting our first child in February. Since I have already stocked our son’s closet full of clothes for the first 1½ yrs. (hopefully he is a normal size baby so he can fit the right sizes in the right seasons… couldn’t help myself!), my husband wants me to stop and start buying diapers that are on sale. This is what I need to know-

-What brands work best for little boys (so far I’ve heard Pampers and plan on buying those)?
-How many diapers do I need in each size? The size thing is confusing! I don’t know if I should buy 1 big box of each or what.
-What is a normal price for diapers? It’s hard to know when you’ve found a deal if you don’t know the normal prices!

Thanks!!