CommanderJiJi

I probably would, since there's some weird things that can happen with undervolting on B-series motherboards if you want to go that route in the future, though if you want to do no CPU tuning whatsoever then yeah, B-series boards are perfectly adequate. 
 
Yes. The price for a decent kit of DDR5 is only barely more expensive than DDR4, so you might as well spend the extra money for a bit of a performance uplift. It's not a massive performance uplift, but it's one nonetheless and you can always carry your memory kit towards a future build, unlike with DDR4. 
 
Where are you shopping and what's your budget? Prices are very region dependent, so one board that might make sense in the US wouldn't make sense in the UK or Germany, for instance. 

Buying an FX6300 is silly in 2021 regardless of how much it costs. It's also impossible to answer your question without knowing the specific PSU model and the rest of your system specs.

dont give finalmouse marketing any ideas.
 
I also believe that a mouse's lifespan is entirelly depenedant on how its used: a mouse used for scientific research will last longer then, lets say, a mouse used by CoreJJ or Faker.

All switches and buttons have a lifespan.  Some are rated for 500k operations and some aren't rated at all.  The manufacturer might have done a durability test on the final product to ensure longevity but I haven't seen much advertised as "good for x number of clicks".  If it has a 1 year warranty then you'll get 1 years worth of clicks for sure. 

Yes, because the button is a physical object and physical objects wear out eventually. No one has managed to invent a mouse that circumvents the laws of physics.

None of that: just benchmarks.
 
Look at how different videocards perform in what you do with your system (gaming, video editing, 3D modeling, etc.) and decide what to get from there.
Then, once you have decided what GPU to get, you can then decide what variant to get (what cooler variant). You decide that based on reviews too; to see which are the quietest for example.
Of course keep in mind the videocard should fit in your case too.
 
And remember that the RTX 3070 is going to release in a month, but expect it to sell it in seconds, plus AMD is going to announce some stuff too; so be sure to check if what you're buying now won't be succeeded soon.

look at gpu clock, memory size and type and also any info from the manufacturer(bad parts?) and also the cooling system i guess
also look at what features the card has (such as the 20 series's nvenc encoder) and see if you can take advantage of it

You're trying to boot to a device with nothing on it, there's nothing to boot to

650ti, radeon hd 7870 or something along those lines. Buying something new would be a waste of money imho.