Help, 1600 vs 1866mhz memory

Hi, working on the following build and had a few Qs(http://pcpartpicker.com/p/1bKXW):

1. 1866mhz or higher memory  really make a significant difference in performance vs 1600 for gaming??

2. Is there any reason to chose one RAM manufacturer over another if specs are same(for eg. is the A-Data XPG fine or should i look at something like crosair)? are there any differences in performace or product life??

3. Can u install Windows 8 from a thumb drive as i can get a legit copy from dreamspark :) and how is Windows Embedded 8 Industry  different from windows 8 pro??

Thanks any other comments on build also appriciated :D

Unless you were planning an APU build it doesn't really effect gaming performance all to much. A-Data RAM is fine, and has a nice price usually as well.

No real performance gain in gaming. Higher frequency RAM is best used for editing.

I would recommend buying 2 RAM modules that total 8GB of RAM. You do not need 16GB for a gaming machine. Your usage probably won't exceed 6GB of RAM. That'll save you some money.

how cheap velociraptors have become, they're not what they used to be anyway (raptorx). It makes more sense to not invest as much in RAM as it makes no real difference (under 1% in performance) and instead spend more into gpu and cpu. 8gb is over sufficient, and I think 1600 is fine for such platform, I don't know for sure. On Asus's specs anything over 1600 is "OC", so it must tamper with CPU settings (I'm not sure at all since it's different than the old FSB). I'm coming from core2duo so what do I know... Anyone care to help?