It all depends on how you post. I don't post anything serious or personal on social media, that kind of stuff happens in the DMs or Private messaging. It's very easy to avoid trolls. I guess my one thing I dislike is when I see a lot of the same jokes reposted over and over again, it makes your timeline real uninteresting. So simply, just connect with more people and more content appears. I also feel like I have to keep up with posting fresh content as well so I'm not the one making the same posts over and over again, it's a god problem to have.
To add onto the other answers, even if this was attempted from someone on earth, it would still be making its journey from Earth to said Black hole. Even if we had something that could be sent that direction from the 1960s, when space exploration really started, and that craft was still traveling out, it'd still be very far from its destination.
I'm not sure. Last time I donated blood I peaked over at the screen the lady was using. It said O+. So if I had to guess, I'd guess O+. But again,, I'm not really sure, I just looked at the screen, there was a lot of stuff on that screen, it wasn't a good look, and it might not have even been my "file" or whatever from prior donations.