Hi,
Unfortunately custom fields have not been added to the custom view of the article add-on yet. It's on the ToDo list of our developers, but I can't give you an indication when this will be added.
Regarding the imge url as text I inform you that this is by design. You need to wrap the image tag inside an html <a> element. Within the custom view you have to add all the html and css classes yourself, so you have full control over the view.