
Is there an old thread or something that covers edits around the city walls?
You get into all sorts of stickyness if you need to remove or otherwise edit the city walls. If you don't need to do that, then it's less of a problem to try and support, but that also depends on where in the city your new additions are planned for. It's easy enough for you to do the rock method swapping. Any serious landscape or path grid changes and you'll be looking at needing two patch files. There's simply no way to merge landscape or path grid data, and the nature of Leyawiin Reborn means that land or grid patches for it will disrupt things with a normal Leyawiin.
Only if you're not running with the proper road record file. If you're using the wrong one, then she won't be the only one you'll eventually find dead at the bottom of that bridge.