I have a couple questions about parts that will be used in my new gaming pc?

1000 watts is enough, you won't need to overclock that cpu. The V-8 is a good air cooler,water cooling is higher maintenance. Have 3 case fans, that is enough. Onboard sound is fine for me, you can add it very easily later. If your monitor is too big your eyes work harder to do the same thing. 19inch is good for me. I sometimes play my games smaller as it's easier and faster. All the parts look good to me.