Do I need anything besides NetBeans source code to be able to compile and run the NetBeans IDE?
The NetBeans IDE includes a number of third-party libraries which are needed for compiling and executing the IDE. See the complete list of components in NetBeans at http://www.netbeans.org/about/legal/code_dependency_matrix.html.
These third-party libraries are included in the source snapshot distributions and Mercurial. Please read license files which accompany the NetBeans IDE.
The extra libraries are included in binary format in the regular builds available for download. You may be asked to accept their licenses when starting the IDE.
For general legal info, visit the netbeans.org legal pages at http://www.netbeans.org/about/legal/.