http://www.gigabyte.com/products/product-page.aspx?pid=4957#ov
1. TWO (SLI or Crossfire)
2. Yes, however I would recommend the Asus Z97-A which I feel is probably a higher quality board (for reliability)
3. Sound is the new HD1150 Realtek audio
4. No wi-fi that I'm aware of but usually you have to spend more than this for included wi-fi. USB or PCIe is available for under $20.
5. 5x PCIe in theory though you won't be able to use most. You'll have either TWO or THREE available after the main graphics card is installed. Which is plenty. Some boards have a PCI instead of PCIe slot as well.
Other:
Nice build. you'll enjoy it a lot. May I recommend you consider:
1. Noctua NH-U12S or NH-U14S CPU cooler. The EVO you have is sufficient but the Noctua will be noticeably quieter. Silent in idle and barely audible under full load (with fan control setup properly).
2. START8 from Stardock
*And setup software (Google) to boot directly to the typical desktop bypassing login and W8 Start scren.
3. If GTX970 is on backorder go ahead and build the system and used the intel iGPU.
4. Setup using "XMP" and save for CPU/DDR3 settings, then run MEMTEST to test the DDR3 memory prior to installing Windows (about 30 minutes for a full pass with 8GB). See motherboard manual for DDR3 installation but likely #2, #4 slots.