Hello my friend. Next 2months or so. There will be new GPUs that will be out and it would be a waste of your time to make a build right now.
Unless u can't wait like me. My advise OP is get a good quality used GPU or find one on sale for a great price so u can sell it when the new GPUs come out. I got lucky and got the EVGA GTX 590 from Microcenter for $500, but like I said that was luck.
A for CPU i5 2500k is best for gaming, along with z68 or p67 mobo.
Mouse depends on hand grip & play style. The RAT 7 is my favorite for FPS. http://www.newegg.com/Product/Product.aspx?Item=N82E16826102062&nm_mc=OTC-Froogle&cm_mmc=OTC-Froogle-_-Mouse-_-Cyborg-_-26102062