1. You will find that the reviews are like that on most motherboards. No matter what, someone, somewhere, is gonna get one DoA and their gonna review it accordingly. I wouldn't worry about it to be honest. As long as there are mostly positive reviews then I would say you are fine.
Edit: Hmm...just went and read the reviews...looks like there are just enough negative reviews to warrant not buying that board.
Check out this one: http://www.newegg.com/Product/Product.aspx?Item=N82E168...
It's cheaper, and seems to have everything you want. USB 3.0 and dual channel DDR3.
2. I'll leave someone else to answer this question
3. Get the XFX card. XFX is known for their warranty and customer service.
Take the cheapest G.Skill DDR3 1600 CL7 one.
DDR3 1600 is faster than DDR3 1333. CL7 is faster than CL9. With heatpread is better than without heatspread. 2 Similar products? Choose the cheapest.
Both are good. XFX and HIS are on my shopping list. Here, choose the cheaper one.
I would go the H55/H57 route, since you are looking for USB 3.0 and IEEE 1394. Here are the four motherboards I would recommend... Newegg Comparison. These provide you the cheapest option for what you need and will work fine with the rest of your system, since you aren't a "gamer".
I would go with the XFX version myself, as XFX is the better brand, plus you get support for Eyefinity.