The "simple" answer is that small cells can more easily transport and transpire materials into and out of themselves. Cells "eat" and "breathe" and "excreet" by virtue of what they can move across...
Yes...and....No...but mainly yes cell damage and death will cause changes in the cell metabolism, but this may or may not have a significant effect on the bodies metabolism as a whole. "Cell Damage"...
Im pretty sure its the white blood cell. it has receptors on it that match the skins of other cells that are supposed to be in the body. those that aren't it envelopes and destroys
The interphase, (which is the period for the cell to increase its size and the number of organelles in it or to get differentiated), becomes very short such that nuclear division occurs very rapidly...