Countdown (Two questions)

Does everyone see the message on the chat or only I see it when I type /online and get a result how many players are online.

Is there a way to count down. I think when someone writes /online that only after 1 min. can type again ?

It only shows to the player using it. There is a plugin for limiting command rates, but otherwise I can look at adding an option for a cooldown potentially.

yZLGktKxc2Wknms.png Wulf

It only shows to the player using it. There is a plugin for limiting command rates, but otherwise I can look at adding an option for a cooldown potentially.

It would be good to put it countdown so that no one would do abuse with plugin commands. 
Is there a possibility for everyone to see when someone writes /online? Which part of the plugin do I need to edit?