I suggest following changes in billingAddressInfo.php to show customer phone and company:
After printing first and last name:
<?php echo (isset($billingAddress->company) ? esc($billingAddress->company) . "<br>" : "" )?>
After printing zip code:
<?php echo (isset($billingAddress->phone) ? esc($billingAddress->phone) . "<br>" : "" )?>
The Open Source portal can be customized as per your requirements and the source code shared is only for a reference implementation. This is the reason why the values of company and phone aren't included by default in the reference implementation.
Hope that helps. Please let me know if you've more questions.