Gaming Computer ($1200) Would appreciate advice and input.

Approximate Purchase Date: Within the week

Budget Range: 1200-1300

System Usage from Most to Least Important: Gaming, occasional music production

Are you buying a monitor: No

Parts to Upgrade: (e.g.: CPU, mobo, RAM) **Include Power Supply Make & Model If Re-using**

Do you need to buy OS: No

Preferred Website(s) for Parts: Lowest pricing (may use price matching on NCIX)

Location: Canada, Ontario

Parts Preferences: Intel CPU, no preference on GPU

Overclocking: Yes, but not immediately

SLI or Crossfire: Not at the moment

Your Monitor Resolution: 1920 x 1080

And Most Importantly, Why Are You Upgrading: Current computer is starting to give out

PCPartPicker part list / Price breakdown by merchant / Benchmarks

CPU: Intel Core i5-2500K 3.3GHz Quad-Core Processor ($159.99 @ Microcenter)
CPU Cooler: Noctua NH-D14 65.0 CFM CPU Cooler ($75.98 @ Outlet PC)
Motherboard: ASRock Z77 Extreme4 ATX LGA1155 Motherboard ($134.99 @ Microcenter)
Memory: G.Skill Ripjaws Series 8GB (2 x 4GB) DDR3-1600 Memory ($38.99 @ Newegg)
Storage: Crucial M4 128GB 2.5" Solid State Disk ($104.64 @ Amazon)
Storage: Seagate Barracuda 1TB 3.5" 7200RPM Internal Hard Drive ($77.99 @ NCIX US)
Video Card: Gigabyte Radeon HD 7970 GHz Edition 3GB Video Card ($413.78 @ NCIX US)
Case: Fractal Design Define R4 w/Window (Black Pearl) ATX Mid Tower Case ($104.99 @ Newegg)
Power Supply: Corsair 650W ATX12V / EPS12V Power Supply ($89.99 @ NCIX US)
Optical Drive: LG GH24NS90 DVD/CD Writer ($16.99 @ Newegg)
Total: $1218.33
(Prices include shipping and discounts when available.)
(Generated by PCPartPicker 2012-08-22 21:38 EDT-0400)

I think I'm pretty content with this build but I'm still new to this and would appreciate suggestions. I have a few questions/things I'm unsure about:

1. I've been reading that a ton of people are having issues with the Z77 Extreme4 board and the USB3.0 ports are actually running as 2.0 (might be just the front headers?). Should I steer clear of this board?

2. Someone recently suggested the Fractal R4 case to me, but I was set on the HAF X Full Tower for a while. Does anyone have any opinions or full case/mid or more specifically, the R4 vs. HAF X?

3. Is Gigabyte a safe bet for the 7970 Ghz edition? Or is there maybe another manufacturer who offers a better warranty/people have had better experience with in regards to customer service/RMA processes?

4. Finally, I've been constantly going back and forth between getting a 2700k, 3770k and now the 2500k or 3570k but I really can't decide on one. (I'm starting to get away from the i7s as I don't really need the hyperthreading).