Prestashop with Paypal IPN or Express Checkout?

[juanpastas]

This question is here.

 

What I have done

 

I read from Paypal site that IPN can be used to:

• Update their inventory.
• Email a purchase confirmation.
• Trigger order fulfillment.
• Enable download of digital media.
• Update their customer list.
• Email a shipping notification.
• Issue a refund.
• Update accounting-related information.

And here is a way to configure IPN for Prestashop. Also I saw this file(3rd link) in a Prestashop Github fork.

There is no IPN in main repository, 4th link.

I read that Prestashop is intented to be used with Express Checkout.

 

My questions

1. Should I use Prestashop with IPN?
2. Where can I read how Express Checkout works with Prestashop?

Questions in case I should use IPN:

1. How to do the most basic setup of IPN within Prestashop?
2. What will this most basic setup do?

I can share only 2 links , 3rd and 4th link will not be here.

Edited February 5, 2015 by juanpastas (see edit history)