Short of boiling-hot water (and maybe even that), any temperature is fine. This goes for pretty much any protein powder, creatine, fiber, etc… supplements.
You could take it without water if you wanted, but it would suck. Put in as much water as you want. Or milk, or iced tea, or juice…
You can blend in fruit, peanut butter, vegetables, etc…
I guess it all boils down to this: it’s a protein shake, not rocket science.
(and regarding when you should drink it… I think it’s okay to mix it up to a day (or two with refrigeration) beforehand, but I always mix mine just before I drink it)