The Alpha uses two cores just as AH2 does. The number may or may not rise during the process.
Yes, the Alpha is more GPU dependent. AH2 relies on the CPU.
The question about requirements has been answered multiple times and the best answer still is "wait until the product gets finished". Some base lines can be given, but they apply to any game. Something like a CPU of two or more cores running above 3 GHz, a mid to high end video card with 1 GB or (rather) more of GDDR5 memory, 4 GB or (rather) more of RAM, Windows7 or newer, a good quality power supply.