Hope to shed a little light on the conversation (easy on the jabs folks). To answer the questions that you asked:
1) Bottlenecking- if you OC your processor you should be just fine. You may squeeze out some additional performance by upgrading your platform, but the additonal performance per dollar compared to a graphics upgrade is most likely going to disappoint you. Rather than speak in generalities, take a look at this
Tom's Article about building a balanced PC. It's a little older, but it uses some cards that are still relevant like the 5870 and 5970 paired with a range of older two and four core OC'ed processors alongside an OC'ed i7-920. What you see is an OC'ed Q9550 putting up the same framerates as an OC'ed i7-920 at 1920x1200 and above.
Now, the i7's do perform better. But the point is that you are not going to get drastically different gaming performance from an i7 platform than you are by OC'ing your current processor.
In this scenario you are looking at spending $350 on a GTX 570 graphics card. This is not such an insane amount of GPU muscle that will be wasted on your OC'ed processor. There are compelling reasons to upgrade to an X58 platform from your current one, but potentially squeezing a tiny bit of additional performance out of a single card probably isn't one of them. I built an i7-950 system coming from a Q6600 but I had a locked down Dell without a lot of OC option that didn't support Crossfire/SLI so it made sense.
2) The reference cards are what you have available right now so they are all nearly identical. You really aren't going to get a significantly better product from any of the brands. That being said, a lot of folks like to stick with brands they're comfortable with or that have reputations for good customer support.
Note:
Corsair H50 and H70 coolers sound great, but don't peform any better than high end air cooling and a lot of reviews actually show them as running louder than some of the quieter high-end air coolers out there. Not to get off topic but check some actual reviews for more info. They're not bad products, just not outstanding- many people prefer a solid air cooler.
http://www.tomshardware.com/reviews/corsair-h70-liquid-cooling-radiator,2757-8.html
http://www.guru3d.com/article/corsair-h70-review/10
http://www.overclockersclub.com/reviews/corsair_h70/4.htm