Asus P6T WS Professional

I'm making a list of components I would like to use in my first computer build. The main purpose of the computer is for gaming and 3D rendering. I am an amateur when it comes to hardware components, so please excuse my ignorance. I was looking at the Extreme Gaming PC build found here as a starting point, and have acouple questions about the motherboard used - the Asus P6T WS Pro.

1 - The specs for the board on the Asus website states that it supports DDR3 2000(O.C.)/1866(O.C.)/1800(O.C.)/1600(O.C.)/1333/1066 MHz, and the memory chosen in the gaming build is Corsair 2000MHz. Does that mean the RAM has to be o/c'd to run at 2000MHz? If I weren't planning on overclocking my RAM, is there any reason not to get a 1333MHz memory set over a 2000MHz with this board?

2 - From what I understand, hyperthreading is processor technology, but I'm confused why sometimes motherboards specify their support of hyperthreading and some do not. Is it safe to assume that hyperthreading is supported in all modern boards? The P6T specs don't mention hyperthreading support, but the gaming build is installing an i7 6-core. So if it doesn't support hyperthreading, wouldn't that be a large loss not getting all 12 processing threads (when needed)?

Thanks for any help or tips regarding my questions.