1) Look, the debate was bad. He's not going to be able to debate Trump again. He's not sharp enough anymore. Trump and the Project 2025 agenda have to lose for the good of the country and I don't think he's got it anymore to run.
2) As above, Trumpism will be poison to America. Evil, sadistic, vile ideology.
3) It's been building ever since the debate. No doubt about it. I think Manchin telling him to drop out was the final straw.
4) I wouldn't expect them to come out and say he wasn't. That's a matter of national security. Hell, they kept Trump's Covid diagnosis under wraps until it came out that he was in the hospital.
5) A very good question, and one I am actually working on in my head. I imagine he has a strong cabinet to fall back on for daily work, but he doesn't want the stress of campaigning again.
6) He doesn't have it anymore to run and beat Trump. It's unfortunate but it's reality. He's old and isn't as sharp as he once was.