General CPU Cooling Questions

[Afromagnum]

I have an i7 4790k with the stock heatsink with which I did the x method to spread the thermal paste. I have a NZXT s340 which has 2 140mm fans on the top-back of the case and the back-top of the case. I get idle temperatures of 32-42 Celsius. My first core runs around 5 degrees hotter than the other cores, the fourth core runs 3 degrees hotter, and temperature spikes upwards of 50 degrees. http://i.imgur.com/G3TNvu0.png I just reapplied thermal past this morning(about 2 hours ago). I stress tested at 100% for 1 minute, and got temperatures in the mid 90's. I use RealTemp 3.70 to monitor temperatures. I use Arctic Silver 5. After playing games such as CSGO or League, the max sometimes reaches the 80's, but when I alt tab it's around 60-70 degrees.
Questions:
-Are these temperature too hot?
-Should the temperature spike to 50 degrees at time. It only happens for less than a second at a time.
-How much thermal paste should I use?
-Would it be a worthwhile investment for a Hyper 212 Evo? The size looks like the torque force on the processor is enough to harm it. The heatsink is so large.
-Should I get more fans?(The case can fit 2 more 140's)
-Why do some cores run hotter than others? (I'm thinking its because of the distribution of the thermal paste)

 

[LukaBoki]

- Nope,they are perfectly fine
- That's probably a false reading,you'll be okay.
- You should put a pea sized drop at the middle of the CPU and just apply the cooler.No spreading the paste or anything.Just install the HSF.
- Yup.
- Nope.
- Probably,but not sure.
- NEVER,EVER EVER EVER!!! do a stress test with the stock heatsink. Never do that.Never.. never..........never.................never (pretend that it's echoing )