The BACnet module's source is closed, so you cannot build that yourself. You downloaded the demo of the 3.0 core, so you can grab the BACnet module from 3.0/web/modules/BACnet, you can just move that into your git/ma-core-public/Core/web/modules and it will be loaded when you launch the core. That's where you got the Meta data source.

You will from build the pom.xml. Right click on it, run as a maven build. For the settings you need to link to the settings.xml file (which is in the other Maven builds you have defined for Virtual and Serial), the target is 'install' and the profile is 'install-module' (from the settings.xml file). This will create m2m2-YourModuleName-x.x.x.zip in git/ma-core-public/Core/web/modules which will be loaded when you launch Mango. Your module's 'loading' is done by checking which definitions classes (those in the com.serotonin.m2m2.module package) are extended in your module, and using them accordingly.

I have just done this again, new Eclipse workspace on the previously fresh computer. I started by deleting C:\Users\Phillip\.m2 to attempt to get it back to perfectly clean. Then I opened a new Eclipse workspace and cloned the projects from Github. I right clicked on the Core\pom.xml and did a Run As... --> Maven Install. I had to set / add my JDK again in Eclipse, through Window --> Preferences --> Java --> Installed JREs, (as well as the nested "Execution Environment" panel for JavaSE-1.8 and 1.7). Then I got some errors about Jars when running the maven install after setting the JDK. So, I did a Run As... --> Maven Clean on Core\pom.xml. Then I closed Eclipse, then deleted C:\Users\Phillip\.m2\repository. Then opened Eclipse into that workspace again, right clicked on Core\pom.xml, Run As... --> Maven Install ... success! Debug configurations.... Java Application --> New, selected project CoreBundle, did a search for Main classes, com.serotonin.m2m2.Main was right there in the list. Selected that, added the -Dma.home="C:\IA\Instance4\ma-core-public\Core" VM argument and started Mango.

Yep, that is a tricky one that will likely be improved in our new UI in Mango 3.0. The reason Local devices are kept separate is that multiple data sources can use one local device. Thanks.