Shelf life depends highly on that bit of "long hair" left on the coconut. You don't need to store at any specific place, just keep it out of direct sunlight or heat that can dry it. You can use it even after a month. (As long as there's water inside). But if you remove that bit of husk from its 'eyes' the life will shorten as weather goes through those eyes quite quickly, probably in a few days if left in open, humid, air. Specially the less mature ones.
DC coconut is different from fresh ones such as what's in the photo. DC coconut is dried and sliced in mills, and then packeted. They last much longer if packed and sealed properly, but we don't use it very much. It's for industrial use only. Also you can't get coconut milk from it.
Fresh coconut is scraped using a hand operated equipment, and is different in taste and texture. Freshly scraped coconut is soft, and has a milder, balanced taste, while the DC coconut is sweet and dry. We loved to hunt for DC coconuts in the house when we were very young, and then break them and eat. Because it's crunchy and very sweet. Lol.
But fresh coconut is what you would like, for water and for milk.
Coconut water was used as a leavening agent in the old days. Even today the village folks use it, in making the items such as "hoppers" "wandu cake" etc. I know they are strange names, hope Google could help there

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I'll take a photo of scraped coconut during daytime. My crappy phone camera photos are like hand drawn charcoal pictures at night.
