Thanks for your request.
You can find DocumentExplorer in ‘demos’ folder as an IntelliJ IDEA’s project. Unfortunately, the demo uses some IntelliJ GUI Layout managers and therefore can only be executed (run) via IntelliJ IDEA. However, we will most likely distribute pre-built JAR of DocumentExplorer with the future versions of Aspose.Words for JAVA. Your request has been linked to the appropriate feature (WORDSJAVA-457) and you will be notified as soon as it is available. Sorry for the inconvenience.
Secondly, yes Aspose.Words supports all MS WORD document formats including DOCX.
Please let me know if I can be of any further assistance.