how to display users username and domain list in a page
Not sure what you're trying to get at - this plugin attaches a clickable link to get all posts for a domain. The username of the post already comes up. Can you provide a picture if this isn't working for you?
I want to display all blog/sites to a separate page
Ah, this plugin can't really be modified well to do that. You'd have to create a new plugin.
Separate names with a comma.