I use Proton's SimpleLogin which is very handy for things like this. I used to use DuckDuckGo's Email Protection which is free. SimpleLogin is however more powerful imo.
Both services allow you to just create a new email address whenever you need one and it forwards to your real one.
Nah that is unrelated to Honey. You're thinking of Pie Adblock which is created by the same people who invented Honey before selling it to PayPal.
if then != iff
After deleting your account, nobody can ever use that username again. (Including yourself)
For point 2, I'm not sure how you mean that but when you delete your account, it doesn't delete your posts and comments.
I think their metrics showing people are deleting their accounts might be more impactful, because there are probably loads of unused accounts naturally.
If then does not imply iff