Thank you for showing your interests in GroupDocs.Annotation for Java and posting your query.
Let me answer your questions one by one:
Just like version 2.0.0 of GroupDocs.Annotations, does the version of GroupDocs Annotations 3.0.0 is a library dependent on GroupDocs.Viewer? Or do I need to download and the declare the library of GroupDocs.Viewer even if my app has GroupDocs.Annotations?
As GroupDocs.Viewer for Java is a completely different API from GroupDocs.Annotation for Java and both have different purposes so you can not get all of the functionalities of GroupDocs.Viewer in GroupDocs.Annotaion for Java,
However for the purpose of displaying documents in application GroupDocs.Annotation offers AnnotationImageHandler and PageImage classes which can be used to display a document in the form of images, you can also use ImageOptions for displaying a specific page or applying different option on the rendered images.
Is there a example using GroupDocs.Viewer 3 or GroupDocs.Viewer with annnotations with the most recently version?
As I have described earlier GroupDocs.Annotation for Java and GroupDocs.Viewer for Java are two different APIs, but GroupDocs.Annotation can render documents in the form of images so, we have a front end project using Servlets in which we implemented the image rendering capability of GroupDocs.Annotation for Java for the purpose of displaying document in the form of images.
Since it is an alpha release of the project so you may not find all of the annotation capabilities but hopefully you will find your desired functionality of rendering documents.
You can download the showcase project for GroupDocs.Annotation for Java using Servlets from the link below:
Hope this clears things up for you.