your 650 is fine, hell get a 180ssd if you can afford it. for reference BF3 is now 27.8GB on my SSD, and that is one of those games that you want to launch quickly. After the final DLC and another patch I suggest 33GB is where it will end up.
yep yep to save money get the 3570k for gaming. You don't gain much with the i7, not worth the cost. Your psu is fine if you don't plan on running a crossfire setup in the future