i updated the checkout and confirm cart pages to fix issues 1 - 3
for the checkout failure issue, i added the following code to the failure page to show the session contents:
<pre><?php @session_start(); var_dump($_SESSION); ?></pre>
the session contains the response from the gateway
string(2061) "2015-02-26T21:28:57ZFailure169cedd376135Security errorSecurity header is not valid10002Error63.015554367"
this means that the API credentials you entered are not being accepted. double check your Express Checkout API Username, Password, and signature to make sure you are entering them correctly.
to edit the API Information, go to WebAssist -> eCart -> Payment Gateway Credentials.