It's interesting how those from northern climates like England, Canada and Wisconsin say to bring less water or smaller/fewer bottles. Those from desert Southwest and the deep South USA balk at the same idea.
I think the OP can figure out how much water he/she needs on his/her own.
Again, to move the bottles up, Topeak makes the
Alt-Position Cage Mount while Problem Solvers makes the
Bottle Cage Height Adapter. I'm sure there are other similar products.
-Tim-