Creating Collections (similar to a folder) can help you organize your library.
When you add references to your Zotero library, it often imports existing tags. You can add unique tags to your references to make them easier to find later.
When you install Zotero, it includes the most commonly used citation styles. If Zotero does not have the formatting style you need, just visit Zotero's Style Repository, on your desired style, and save it to your Zotero style library.
The style will be uploaded to Zotero and available for you to use.