Random twitter message format for each post

I’ve got two questions:

1)is it possible to use random message formats to publish to Twitter? On every post there is a WP Twitter auto publish section and there’s a message format for posting section in the plug in settings. I would like to manually random text in tje auto publish section in each post so that my twitter publishes message is not the same every time I post. But when I set my tweet text in the auto publish section in a post, it is override by the text entered in the message format for posting section in the plug in settings.

2)in the general section under Auto publish on creating posts/pages/custom post types there is an option Use metabox settings. What does this option do?

Thank you.