4. I always think of BTT as a highly valuable platform. I'm in fear that my BTT account would get compromised someday if I saved my password in an online place.
It is a highly valuable, but not to people that do not know about it. A regular cybercriminal or criminal who comes across your bitcointalk account password will not be interested in it if they do not know what it is, and if your account is low profiled especially.
So I never saved my password anywhere. (I know I should have used a diary to note down my password.)
You forget easily like you have identified, not keeping your password anywhere is a terrible choice to make. If you cannot recover it any day things get mixed up in your head, your account is gone.
Write your password down in your dairy in a format that nobody will be able to decipher. Just devise a means that only you know.