Great advice here about packing. Seriously take only half of the clothes you THINK you'll need. Make sure the stuff you do pack is travel-friendly. There are irons and ironing boards located in the laundry rooms if you need to touch something up. We always end up buying some sort of clothing on an island or two, and then wear it on the ship. You're gonna need room to bring that stuff home.
We've found juice available in self-serve dispensers on the ship. They've usually been labeled just at breakfast. (I just get mine in the Drink of the Day)
I know it's a little pricey but there's usually a big bottle of water on the counter in the cabin. We take it on the island, and yes we refill it from the tap in the bathroom.