RAM Compatibility

Hello,

I have 3x2GB three channel memory (CORSAIR 1600MHz) installed on Gigabyte EX-58-Extreme mother board and I want to upgrade it.

I have found these 4x4GB GSKILL 16GB RIPJAWSZ DDR3 1600MHZ quite cheap. (http://www.gskill.com/products.php?index=427)

So, my first question is if I buy 4x4GB RIPJAWSZs, will they compatible with my motherboard?
Second, there will be 2 empty RAM slots, if I put 2x2GB Corsairs into these slots (20GB in total), will my motherboard support this configuration?
If this configuration operates, how would be the performance? (dual/3 channel?)
Do you have any other RAM suggestion for my case?


Any help or advice is appreciated.
Thank you.