Help deciding on high end gaming laptop? ($2000)

Hi! I just finished building my gaming desktop (with the help of this forum!) which I love, but is huge and heavy so I want to get a laptop for carrying around. Right now I am looking at sager (planning to buy from xoticpc), and am thinking about np9370 because I want to get dual gpu - since it's a laptop I'm assuming upgrading it over time will be a pain? so I want to actually give it better gaming specs than my desktop (i5-3570k, gtx 670 ftw).

Also, my boyfriends cheap dell laptop he uses for gaming has been having a ridiculous amount of issues lately so I am planning on gifting him this laptop to use until I build him a desktop around black friday; so, even though this is suppose to be pure gaming he will probably use it more as a desktop replacement. I'm also planning on maybe processing videos on it as not to waste the i7.

So if someone would be kind enough to answer some questions for me...

1. The price for dual 680m is kind of insane to me so I was thinking about instead doing dual 670mx or dual 7970m (though I prefer nivida I am willing to try amd). Which one would you guys recommend performance wise? Or should I just say screw it and get np9150 with 680m?

2. Will getting the os on a SSD drive matter that much for a mostly gaming build?

3. Pretty clueless for wireless cards, but since for the past 15 years of my computer using life I have never been in a situation where I had regular access to an ethernet I'm guessing good wireless card is important. What is the difference between the stock internal 802.11 vs. intel centrino advance/ultimate vs. killer wireless-n 1202/1103?

4. Just a general question, 17" or 15.6"? I personally wanted a 15.6" since I actually have a super annoying to transport 20" laptop, and miss carrying around normal sized laptops, but it seems like dual gpu is only available for 17".

np9370 - http://www.xoticpc.com/sager-np9370-gaming-laptop-clevo...
np9150 - http://www.xoticpc.com/sager-np9150-clevo-p150em-p-4341...

Budget: ~$2000

Suggestions on better laptops is welcome too!