I think it's time Maggiordomo to be white-listed by the mods so you skip the cool down time between posts.
What is the current restriction for member regarding this? 
I'm not sure if whitelisting would lower this.The minimum (for 500+ Activity) is 4 seconds.
Is adding "banned" status on banned member requires a lot of coding? If not, can theymos enable it? Or why don't he enable it already?
Several users (including me) have suggested to set the Rank to "banned" (oldest reference). It's not going to be implemented any time soon:I'm not going to respond here in detail to all of these ideas. It'd be extremely long. I will classify them as OK/maybe/no:
(quote shorted to the relevant parts, click the link for many more suggestions)Quote
A publicly displayed 'banned' rank under a person's username for permabanned accounts (people are wasting both theirs and staffs time reporting already banned users and bots).
No. Or not yet. Or the idea would need to be significantly modified.