[kh99]

1) In admincp, User Profile Fields > Add New User Profile Field, and set 'Field Required' to what you want (probably 'Yes, at registration and profile updating'). Also I think if you want to display it on the postbit it can't be 'private' (but if you're displaying it than I guess you wouldn't want that anyway). Then in postbit you should be able to use {vb:var post.fieldX} where X is the profile field id. But I didn't try this before posting, so I might be remembering wrong. Sometimes I think that's going to work and it turns out the data isn't there unless you explicitly do a query for it.

The second one's more difficult. Maybe the easiest way would be to have a second field as the login name (Maybe a profile field or maybe you'd have to add a custom field), then modify the login code to use that. I'm thinking that may be easier than making a special display name because I think the login name is only checked in one place but the username is displayed in many places.

But anyway I guess that doesn't help much in knowing how to do all that. I know people have made a relatively easy change to use the email address in place of the username to log in, so probably the harder part would be to add the custom login name field.