Shoutbox

I don't have the time to search at this moment, but both questions are already answered in great detail and with examples on this scripting forum.

For the first one. Use proper methods, not the 'on liners' you'll often find or which people suggest. You need to take several things in account when you close Messenger by script. And you should not force it.

For the second, this is quite easly and involves sending the correct command ID to the main Messenger Window. But again, this requires to take some things in account like Polygamy.

There are already complete example script snippets which do both those things in the proper way (without forcing anything and taking in account the stuff which needs to be taken in account). Search forums... And for exiting Messenger you'll normally should be able to find a script for that in the Official Scripting Database (which adds the /exit command iirc).