This doesn’t sound like an off-the-shelf plugin – rather something that should be coded directly (though perhaps a plugin could be made from that!)
If it was me, I’d start with a form collecting the data I needed (perhaps use a form plugin for that).
Then make use of a few of the WP functions such as wp_insert_post (with your custom post type), add_post_meta (with the new post id and whatever special fields you have) and wp_create_user to create the user.
You’ll need a couple of others, but that should give you the rough shape.
Regards
John
