Scans_Daily

1 & 2) The original anime branches away from manga storyline after the first arc, and while the original anime has an ending of its own, the second anime has none. In original anime, Ciel doesn't die, but he is kinda screwed over, and another major child character dies. In the second anime, there are many child deaths. Furthermore, in the manga storylines not yet adapted into anime we see a lot of child abuse and child deaths, and when Ciel's exact backstory is finally revealed it's EXTREMELLY triggering on multiple levels. It's a very dark series, and from what you said probably not for you.
3) The character is portrayed as a tragic monster, but their actions are never portrayed as right. A later character who kills and abuses children gets no sympathy though.
Many fans dislike the series' resident trans woman, but I think she is the coolest shit ever and I am a trans person, so YMMV.