I don't have a clue about the call signs but B52's have been flying in and out regularly since the 50's, I think the fact that its in the news is more to do with media hype as anything else as its not unusual at all, more than anything else the media are in danger of giving Putin an excuse for invading the UkraineI was quite surprised that the B52s were using call signs of Hate11, Hate12 etc.
I don't think I've ever seen that sort of call sign beforehand.
When it comes down to it even with all the modern upgrades in electronics etc what the B52 is good at is being big, heavy, flying high and being imposing none of which is a serious threat to the ruski's