they can, yes, like out in the desert, because there is so little water there, if any at all, life is unsustainable for trees, but if you have a tree growing in your house, not watering it will definitely make it dehydrate.
Most trees which are trees are trees, also when they're not. Sometimes a tree which is actually a tree but a tree afraid to admit he is a tree is called a busheee.
draft - assuming you mean graft a pear tree to a wild tree in the woods an(d) what can/kind of tree is it? Assuming the wild tree is the same genus (Pyrus) then yes its possible. The two plants will...