Hello ,
Thank you for posting in the community. We have an Auto-Sync feature but it does not synchronize the camera view in Twinmotion viewport. I recommend you make a suggestion on our road-map for this feature to sync the camera view/screen.
https://portal.productboard.com/7pu88c9kpmqtzt8hwg6arujh/tabs/4-under-consideration
There is no way to represent 3D lines and I think that is a current limitation with the engine. I think the only way would be to model those lines or to create a texture with the lines. You could make a 2D elevation in SketchUp then export/save an image and create a texture with a photo editing software then apply it to the surface.
Kind regards,
Vincent B.