Kk look I don't really care about photos so I haven't looked into what exactly is going on or exactly how to make this whole thing work, or whether it even does work at all, so I've been approaching it as kind of a dumb layman, which is probably the average iPhone user's experience:and why? Apple has it off by default.
Not if you're using also Photostream.I'm not going anywhere near it right now, especially since it's still in "beta". That basically means you could lose all of your photos and Apple would say, "Sorry, this feature is still in beta. We can't help you."