You can't overclock the 3550. Make it a 3570K.
I don't recommend that mobo. It can't handle 670 SLI, which is a logical, economical future upgrade, as its second PCIe slot is 2.0 x4. Go for an ASRock Z77 Extreme4 instead: http://www.newegg.com/Product/Product.aspx?Item=N82E16813157293
Make sure the RAM is 1600mhz. That's the value sweet spot.
Yes, it'll just about max those games. Skyrim will be easy, and BF3 and Crysis 2 will be pretty solidly maxed (70ish fps, maybe occasionally dipping below 60). Source: http://www.tomshardware.com/reviews/geforce-gtx-670-review,3200-6.html
Yeah, the 670 is kind of insane. It's a high-end breakthrough in value.
What's the model of the PSU? A good 650W box would be fine for two 670s.