Up-voting Would be great - is a bit depressing to see Asana has flow integration already. I'm doing it with a rubbish work around creating an email out of Flow to Wrike
You almost already have this feature! - When you create a subtask it searches for already created tasks. The searching is there but just needs to be made available in the comments/description areas.
Internal comments would be great. My reasoning is much simpler; sometimes I just want to nag/remind my developers about a task without a client seeing this.