Using external URL for images in posts

Hi

I’m trying to display my featured posts on my homepage and also display the first image from the post on the homepage.

Sometimes, an external url is used to display the image in the post but when I try to use some php code to retrieve the image it only displays the url.

Is it bad practice to use external urls for images in posts? Also, does anyone know how I can get the image to display ont he homepage and not just the url.

I am developing locally therefore unable to share any proper links. This is a copy of the php code I am using to try to display the image.

This is in the functions.php

[Code moderated as per the Forum Rules. Please use the pastebin]

I am using a child theme of Twenty Ten.

Many thanks