a) When you run the cehckout wizard, select the No Gateway option and the checkout pages will not include the credit card details
b) The success page will include code similar to this to write the first name:
<?php echo(WA_getSavedFormValue('CheckoutWizard_NewFromBlank_Default','First_Name')); ?>
you can add another php block to echo the email address:
<?php echo(WA_getSavedFormValue('CheckoutWizard_NewFromBlank_Default','Email_Address')); ?>
c) eCart does not have support for making the success page responsive., you would need to manually edit the page css to accomplish this.
d) on the success page, add the following code near the closing </body> tag:
<?php echo($_SESSION); ?>
this will write the session contents to the page, and will include the status of sending the email.
if the status says successful, you will need to contact the host to determine why the SMTP server is not relaying the email message.