In a pinch for time, so can't write very much. PE4L is better, due to lower price. Both PE4L 2.1 and PE4H 3.2 have 1.2 Opt support. 1. Both will work, PE4L and PE4H are basically like the PCI slot on a desktop motherboard - you plug GPU into this, and connect other components to the PE4L/PE4H 2. Yes, as stated above, boith PE4L and PE4H will work. PE4L 2.1 or PE4H 3.2, PE4L is recommended due to lower price 3. Yes hope someone else can re-address your questions and explain better. Just wanted to give you quick answers to you have a general idea.