Yes, the 6.0.5 upgrade has been released, uninstall the previous version before installing the one in the extension manager.
It is by design that the pp confirm page will be blank, the work flow in eCart 6 is:
user files in checkout form, which calculates shipping, user is directed to paypal to checkout, they are directed to the pp_confirm page which processes the transaction and goes to the success or failure page.
I have forwarded your comments about the lightbox to the marketing department.