I apologize for the stupid question, but if I install this will I continue to receive OTA updates once they are available? If so, will they be received for Slovakia (ORX) or for my country Bulgaria (BGR)?
Just as long as you install with HOME CSC it will update fine.
I suggest you to use Frija , the samsung official firmware downloader. You can select the region you want and get the latest available firmware released for that region.
I have the same thing m8. Strange thing is if I connect the charger in, it works fine. I tried it with charger connected 4 times and it worked every time.
Because it is supposed to work that way.
I was advised to use FRIJA, download is faster, recovery due to connection loss is done by the application. You just need to install the same to your computer.