1. Agreed with Birk - no issues. I don't see PCIE 3.0 being very useful for at least one year's worth of GPUs for now, so I wouldn't factor it in that much. If there's other reasons for getting that ASRock (price seems great for it), go ahead though.
2. I don't quite get the question but if you mean it literally (e.g. SATA 6Gbps SSD caching for a SATA 3Gbps HDD) then the answer is no, there won't be a difference.
3. Get the Seagate as it looks like the newer / not cheaped out drive (32MB cache). The 320GB WD has a 16MB cache which may mean it's an older generation Caviar Blue. (The cache doesn't actually make a difference, but you'll notice an older gen hard drive when your system ever has to use it.)
__________________  "The computer programmer says they should drive the car around the block and see if the tire fixes itself." [src] |