1. Lightroom will not be able to find it. In this case, you will have to point LR to the photo's new location and new name. Important point: Lightroom is not a file browser. Important point: Once you import a photo into Lightroom, all management of that photo must be done in Lightroom.
2. It makes NO sense to organize the photos in your operating system, because you have much more powerful tools in Lightroom. It makes 100% sense to import the photos into Lightroom and then use Lightroom tools, like keywords and other metadata, to organize the photos. Keywords and other metadata were specifically designed for photographs, while folder names were not. Keywords and metadata allow your photos to be organized in many hierarchies (e.g. who, what, where, when and others) whereas folders allow you to organize in at most one hierarchy. Keywords and other metadata allow you to do searches that can find photos that are scattered across dozens of folders; such a search is nearly impossible in your operating system. So ... leave your photos where they are, and import them into LR in small batches, and begin adding keywords and other metadata to these photos. From now on, organization occurs in Lightroom with keywords and other metadata and not via folders or file names; searching occurs in Lightroom; browsing occurs in Lightroom; and file management occurs in Lightroom.
