It's a great build, just make sure to get a very good quality PSU, do not cheap out on that. Also, if you're stuck for money, you could cut the RAM down to 8GB instead of 16GB unless you specifically need that amount.
RE your questions, there's no problem there, you'll get your specified RAM speed as long as the Mobo supports it and the RAM is DDR3.
Thanks for the reply, which brand of PSU do you suggest? cause I haven't decided yet.
So what does the RAM limit in processor mean??