Cooling Systems, are they so important?

Just below "melting point" is probably 80 degrees C. I don't think I would want mine that hot. If you are going to spend the money to build one, it should be one that runs cool. Get a case that has a place for fans on front, back and side. This will give you good ventilation and the price difference between a cheap case and a good one is not very much.

Agreed. and if you are worried about the cooling, an aftermarket heatsink is way better than the one that will ship with the CPU.

Sometimes, CPU and GPU (especially in notebooks) will implement throttling. what this does is if the temperature reaches a certain point, the CPU will automatically throttle back the CPU so that it doesn't get damaged. This is not as common on home-built PC's as in notebooks and OEM computers.

melting isn't the only risk. the PCB (the material the components are soldered on) and the components themselves degrade when exposed to extreme heat. A good cooler is friggin cheap compared to even a bank of RAM, don't skimp on it.

also, did I read correctly? 32 GB of ram? Really? Even badass servers rarely need so much ram. and that build is more like a gaming rig (a bit overpowered if you want only to do HD video editing).
Don't buy more than 16 gb of ram and invest in a good SSD instead.

In my opinion it's one of the most important factors of a build and that is almost always over looked. It's almost never consider until after the fact. So...yes it's very important. A good quality case that has great air flow options is a must in my book from the start. It's a lesson for some that is learned the hard way with premature hardware failures and system crashes.

For me two things to never skimp out on is a Computer Case and a PSU. A great analogy and another way to look at this is your home entertainment system. You have all these high end components...HD TV, surround sound, DVD/Blu-Ray player all connected to some cheap power strip that's not ever surge protected....and probably the same for most users with a computer system. You have to protect your electronics, all of them with a high quality surge protector.

I can't even believe the question. Of course it matters unless you are building a one time toaster. You will have to do your homework on cases and cooling. CPU's and cooling and Vedio cards and cooling before you ever think about building a HD video editing computer. H80 will work well but I would use Noctua fans push pull. As Bassfisher has mentioned you also will have to do a lot of homework on selecting the proper hight quality power supply. I recommend doing you homework before doing your shopping.

Well, they don;t really matter, unless you want to keep your PC from frying components.