ikem,
That motor should swing a 10x4.7 easily -- do you want to go smaller?
The only advantage I see of underpropping it is if the 10" prop is ovelapping the quad's body and a smaller one wouldn't, or you wanted shorter booms. A 450 quad frame, however, should easily accomidate the 10" props. Otherwise, if it's generating too much thrust, you can throttle back. you'll loose some of the resolution on your throttle control, but likely not enough you'd notice it.
The ESC is a bit overkill, but if you don't mind the extra weight/cost, it won't hurt anything.