After a user submits the registration, he should be automatically redirected to a confirmation page. If you are not seeing that confirmation page, what exactly are you experiencing?
As far as I know, the only way to customize the registration e-mail is to edit the `register_user` plugin. The message can be found on line 198 in the file. If you do not feel comfortable editing this yourself, feel free to open a ticket on the bugtracker as this seems to me to be a viable request.