Upgrade Ready - last check

Hi all,

I'm about to pull the trigger on upgrading my current PC and just want to get confirmation all the parts will fit/are compatible.

Long story short, i was gifted an Acer Predator (1440p 144hz) monitor and can't afford a new pc yet. I want to upgrade what i have to make the most of my new monitor. This will be used mostly to play DotA 2, CSGO, ArmA 2 and Overwatch.

Current PC:

1 ASRock Z77 Extreme4 Motherboard 1 Intel Core i5 2500K (OCed to 4.2ghz) 1 Corsair Hydro Series H40 CPU Cooler 1 Fractal Design Arc Mid Tower 1 Silverstone Strider Plus 750W ST75F-P 1 Samsung SH-222BB SATA DVDRW Drive OEM 1 Corsair Force Series 3 120GB SSD 1 Seagate Barracuda 1TB ST31000524AS 1 Sapphire Radeon HD7870 2GB GHZ Edition OC 1 Corsair Vengeance CMZ8GX3M2A1600C9 8GB (2x4GB) DDR3

Upgrades:

RAM: https://www.pccasegear.com/products/21770/corsair-vengeance-cmz16gx3m2a1600c9-16gb-2x8gb-ddr3

GPU: http://www.newegg.com/global/au/Product/Product.aspx?Item=N82E16814487244&nm_mc=KNC-GoogleAUAdwords-Mobile&cm_mmc=KNC-GoogleAUAdwords-Mobile-_-pla-_-Video+Card+-+Nvidia-_-N82E16814487244&gclid=CIPjirHm584CFZSUvQodMBAGuw

Apologies for some potentially dumb questions, but I'm still learning a lot of this stuff.

1. Is this ram compatible with my mobo?
2. Is there anything wrong with this brand of GTX 1080? It's the cheapest 1080 on the Australian market by almost $200 - is there something about it im missing.
3. Do i have enough power to run the GTX 1080?
4. Is there anything else I'm not considering/missing?

Appreciate the help.