You'd be wrong to. Omniscience is not necessary for any of those things. In fact modern medicine does a pretty good job of the last 2. We're working on number one. ;)
Anyway I was not contending that Jesus was or wasn't omniscient. I was merely contending that I could imagine a Christian believing that Jesus the man wasn't omniscient.
Just because Jesus was omniscient, doesn't mean He would have to use His omniscience while on Earth or at least not constantly. How can you be omnipotent if you can't shut something off when you want to?