i5-2500k is the same as i7-2600k in gaming performance.
All the motherboards you listed are considerably "overkill" for your needs. Something like ASUS P8Z68-v PRO or ASRock Extreme4 GEN3 or Gigabyte UD3 would be fine, all supporting SLI at x8/x8.
RAM: SandyBridge (socket 1155) motherboards require dual channel RAM, so stick with 8GB but look for 2x4GB sticks. 1600MHz, CL9, 1.5v recommended for best price vs performance.
Graphics cards - If you think you will upgrade in the future and add a second GTX 580 in SLI, go with a single GTX 580 now and leave that upgrade path open. If you plan just to build and stick with it, SLI 560Ti's will cost less and give better performance in the initial build. Either way, both options will give you more than enough FPS at ultra settings on 1920x1080 resolution (FULL HD).