1) This should've been posted in the Scripts and Pop-Ups section, especially since you knew it was going to be a script, per your subject line.

2) This script presumes that you use the same password for all of your nicks and that the nick registration service is called nickserv.

Code:
on ^*:notice:*is registered*:*:{
  if ($me isin $1-) && ($nick == nickserv) {
    .msg nickserv identify <password>
  }
}
on ^*:notice:*You are now identified*:*:{
  if ($nick == nickserv) {
    .msg chanserv invite <#channel>
  }
}

You may need to edit these for the actual messages, as well as the network and channel names.