need opinion and criticism for choice of new laptop

I have decided to buy a Lenovo G50-45 with AMD a8 6410, 4gb ddr3 1600 mhz, 500 gb, win 8.1, i plan on adding another a 8gb ddr3 in the extra slot, as for the laptop( only lappy), the max i can spend is around 400$ , my prime requirement is coding , i am learning to code c, java, c++,etc, maybe a bit of VMs for trying out other OSes, and i used to play a lot, but recently my desktop from 2010, c2d e7500, nvidia 630gt 1 gb ddr3 and 4 gb ddr2 isnt supporting any, so i might even try to play games like ac unity or cod advanced warfare, but the chances of doing that are very less. i will carry the lappy to college for watching tutorials. i have heard amd processors tend to heat a little too much so planning on getting a cooler too ( cheap one ),but cant carry that to college, so i would like your views on any amd heating issues i will face and is there any possibility i can add an external pcie express slot( or whatever it is called) to my lappy to connect the graphics card of my desktop to this, also i would like to know how adding that extra 8gb will help, and lastly would you recommend any other laptop in my 400$ price range.

need opinion and criticism for choice of new laptop