The latter undoubtedly would have screamed to Joel "I gotta detach myself from this kid, if I ever cared for her the way Henry cared for Sam, I'm gonna kill myself too" especially after it pretty much confirmed Bill's warning about it "blowing up in his face".
Yes and no. I'm not sure Joel cared that much about his life. He's a survivor, but, i think what scared him the most was his feelings for Ellie, not the possibility to die, and that's the reason of why Tommy finally agreed to take Ellie with him.
Interesting video with the original script. Start at 25:48. Ashley/Eliie asks to Troy/Joel what he's so scared of, and Joel answers "Because I'm a big coward". Since Sarah's death, Joel fear to get too emotionally involved with someone else and he knows if he stayed with Ellie, this is what is going to happen. You're right, Henry's suicide and Sam death has certainly influenced his decision.