Hi Kendall!
Even though you are using the custom fields to collect additional information for each attendee, the RSVP confirmation will only be sent to the email in the standard “Send RSVP confirmation to” form – that user will receive a copy of all of the tickets for the people he RSVP’ed for. If you wanted to remove that block, you would need to add code to instead have the email sent to each of the other emails from your custom fields. Customizations like this are outside the scope of support that we are able to provide here in the forums, but this post has some suggestions on where to start if you would like to go this route.
Regarding changing “RSVP” to “Register”, you can do a template override (not involving the functions.php file, although you will need to be able to upload files to your child theme via FTP) of the rsvp.php file – look for this code, which is the code for the “Confirm RSVP” button:
<button
type="submit"
name="tickets_process"
value="1"
class="tribe-button tribe-button--rsvp"
>
<?php esc_html_e( 'Confirm RSVP', 'event-tickets' );?>
</button>
In your copy of the file, you can change the “Confirm RSVP” text to “Register”.
Let me know if you have any other questions!
Thanks,
Jennifer