1: As far as thermal paste, you may want to look at this graph. Prolimitech pk3 is only like 8$ and seems to work much better then the arctic silver 5.
http://overclocking.guide/thermal-paste-roundup-2015-47-products-tested-with-air-cooling-and-liquid-nitrogen-ln2/6/
2: Go with 2x4 sticks of RAM. unless you are doing rendering in 3ds/maya or something you really shouldn't at this point in time need more. Almost all motherboards will benefit from 2 sticks by a good amount for performance( it effectively doubles the bandwidth.) As far as the mhertz rating though, it doesn't make a huge difference from what I've seen.
getting 2x4 will also leave you able to buy another copy of the set for 16GB if you need it down the road.
One thing to really pay attention to, is if you do go with the 212 evo, it can sometimes block off one of your ram slots because of its size. Look up your motherboard combo and the 212 evo in research that.
3: I prefer the cooler master jetflow series fans as they move more air, but the ones you choose aren't bad either.
4: I found your cpu cheeper on newegg
EDIT
5: Just to go on with the motherboard stuff above, make sure it has at least a 4/5 rating. There are a lot of motherboards in the world, and some of them die 4 months into use, after your RMA time is up.
This board should hold up that cpu and gpu fine, unless you plan to crossfire later on.
Although, if you want an msi board color theme that matches your gpu, this one will fit in.