We use a combination of stock textures and some custom ones that still mesh well together, so this may be why some textures may appear lower res. The Black Parade isn't compatible with graphics mods. The campaign was not designed with any of them in mind. You can still use them if you want but you'd have to do it manually.
According to the official statement from November, significant progress have been made in the recent months and the campaign is closer to completion, though there is still some remaining work to be done and the team wants to prioritise quality over rushing with the release. They have an undisclosed release schedule, so you can be sure the campaign will be out at some point in future, just be patient.