1) The original one is for C++, just pick up the DarkGDK.NET version, as you said you are exclusively a C# developer (just like me).
2) The addons are exclusively for DBPro. About extends, one of its systems, the Dynamic Media Handling has a better replacement if you use my LightEngine plugin for DGDK.NET, as it also adds full OOP to it. Better info on
www.lightorb.net.
Also, I'm working on a GUI plugin that will also contain bitmap font handling (replacement for XGui System and XFont System). About other systems on eXtends, there's nothing else similar I'm planning to work with this time, but most of the others are not THAT difficult to implement.
3) I didn't get this one right, but if it is what I undestood, DGDK.NET can identify every limb (subsets, like Head, Torso, Arms, etc. in a humam model for example.) on a 3D model and you are allowed to make small changes to each separately.
Hope I could help, anything else, plenty of people here will try to help.
Best regards,
Thiago