Here in the Netherlands my level of German is widely called "steenkolen Duits" (coal German) because it's course, harsh, hard and dirty)
That's actually not the etymology. Steenkolenduits (spelled without a space) is a riff on steenkolenengels, which was the basic/broken English spoken by dockworkers with sailors on incoming British coal ships (steenkolenboten).
Or they just expend their effort on the browsers that 96% of people use and not the one that 4% use. I love Firefox, but I don't think this is the conspiracy you're claiming it is.
You definitely shouldn't need to do that, one account is enough.
Maybe you're confused because communities can be on different instances (servers). But you don't need to make an account on those instances, because all the instances are federated together. That means you can just have your account on one instance and follow and participate in all your communities from there.
Some BIOSes have trouble booting anything other than Windows, so some distros default to clobbering the Windows Boot Manager and trying to manage everything from GRUB. It sounds to me like this is what happened to you except it somehow got borked.
If the Windows install is still present on your drive it should be possible to restore the Windows Boot Manager. Then you won't be able to boot Linux but you'll at least be able to get into Windows.
Does it work well?