Velja

Under load in a laptop yes. It's a small space, it WILL run hot.

CPU's and GPU's aren't often under continuous even loads, this is expected behavior. it's only concerning if spikes are rapid and lead to a noticeable performance issue when using the computer day to day.
Unlikely. You don't need a lot of thermal paste and using "too much" can only create a mess at worst. 99% of thermal compound is non conductive so it's unlikely to damage anything if you use a mound of it and it squeezes out onto the motherboard.
 
TLDR; if you're using the device and it's acting normal, don't worry about the spiking.

When picking memory, you will usually see the best performance, with faster memory. But performance is a combination between mhz and cl. Where most gains are usually gained trough faster memory (mhz). When 2400 mhz is your hard limit, look for a lower CL to get gains.

Higher CL == bad. You want that as low as possible.
 
If your CPU max ram speeds are valid, go for the 2400 mhz memory.

Use a live bootable Linux and run in that for a little bit. That will help narrow down if it’s Windows or a bad install many times. 
You could also boot into Windows Safe mode to either eliminate driver conflicts. 

Record what is happening. Like the whole process of you getting BSOD.

At this point, I'd recommend a fresh install. But looking at
Did you upgrade from windows 10 or was it a clean install? If it was not a clean install, I'd recommend doing so. Since you have stress tested every component after the system is stable and it does not crash, hardware can be put aside as it does not seems to be causing the failure.

You can even dip it in rice for a day or two

I had the same problem, i installed Advance System Care and it fixed the issue and i think there was a problem with defragmenting the HDD or with some apps running in the background, so i would recommend to give it a try, if that doesn't help try and see if your temps are oke and that your CPU or GPU arent running hot. I rly dont think its the CPU kuz mine is worst and its not bottlenecking.