Q1 - Not really, well it depends on the manufacturer. Some manufacturers like to cut corners when it comes to thermal paste, or psu cables for example.
Q2 - Download a program called 'HWiNFO' and select 'sensors only'. Scroll down to the DTS section for your cpu and notice the temperatures. Anything over 80 or 90 degrees could be thermal throttling, it depends on the cpu, as of my knowledge most intel chips start thermal throttling when they get to 95 degrees I think? You can run a stress test program like 'Prime95' or 'Aida64' and then monitor the temperatures in HWiNFO to test further.
Hope this helps