You can bump up to an i5-2500k for $20 more. The i5-2500k is an incredible overclocker and will give you ~95% of the power of an i7-2600k.
Running two cards in x8/x8, you'll see almost no performance drop versus x16/x16 (maybe 3-4%).
As far as RAM is concerned, I've picked out a kit with CAS Latency 7, but you can save $40 with a CL9 kit. There will be very little real world difference in speed.