authorize net Links Checkout Wizard Remote Processing

I've been following the excellent tutorials for eCart 5. I'm not finding anything for setting up the checkout for authorize.net to handle the processing remotely. While going through the steps Checkout Wizard, I specified remote processing and as attached, it defaults to the localhost settings.

1. Am I to assume that Site address and Local folder is something I need to obtain from authorize.net?

2. I'm not actually creating any pages on their site am I? That's something they already have in place? In which case I leave those fields blank?

3. Is there anything I need to do to get the customer back to my site once the transaction has succeeded or failed, as far as eCart is concerned or is that all a function authorize.net has in place?

Thanks