No, I would never be open about wanting to die, doing such a thing would be a terrible idea, there's no benefit to that. They never need to know anyway, it doesn't concern anyone else how I feel about existence, I will always see it as better to stay quiet, I've always been quite a quiet person, I've never really liked talking much anyway.
I feel kinda similarly... if I was truly contemplating death, I don't think any good would come from people around me knowing. Mostly, because, I wouldn't want anyone to get alarmed and try to prevent me either or force me into some treatment against my will. But, also, I think it'd be unkind to people that care about me, hearing me say stuff like that because it'd be really serious and stressful for them dealing with that kind of information. -Though, I have shared with close people before that I had a failed suicide attempt... but, only because it was a past thing and I seemed to be over it (happened many years ago). Any real, current desires about dying or suicidal tendency, I'd probably want to keep quiet about it... the most I'd reveal/hint at is that I'm feeling very depressed.
Discussion: "Will you leave a goodbye thread and / or a note?"
I don't think I'd write anything on the day of, because I wouldn't want anyone being suspicious and checking up on me. Maybe, I'll send text messages to some people just generally appreciating them for their time in my life, a couple days leading up to it. I probably won't leave a note for reasons why I did it though, because I wouldn't want anyone blaming themselves... even if it were the case that some people had hurt me, it'd be pointless to point fingers after death anyways. I'd just be thankful not having to feel so much sadness/emptiness anymore.
I'm not sure about a goodbye thread on here. Maybe, I would, if over time I felt comfortable and got to know the community better and made friends (or used a method I'd learned from here). It could be a way to update what happened to me, instead of just disappearing suddenly if I was active enough.