I have the source code to David Rose’s Tagger sample lying around somewhere. There is also this, made by @wolf:
And these, which will likely make it into 1.11:
It stood for Disney’s Interactive Real-Time Environment Construction Tools. It was one of several libraries (one other being PANDA—also an acronym!) that they used together. When Panda3D was open-sourced, they were packaged into the same distribution.
Generally, DIRECT contains more high-level code that is implemented in Python. We generally try to be more inviting to C++ users nowadays, so we try to implement things in C++, except where there is a clearly established precedent.
For now, I wouldn’t worry about it and simply use direct as needed in your samples.
This is fine. I think it is too early to think about further reducing the polygon count. This is a fairly simple model so it might make more sense to demonstrate LOD using a more complex demo piece.
A great way to make a multi-LOD-level model in Blender, by the way, is to use multires modelling, where you start with a coarse shape and subdivide it over time to add more detail. With this feature, Blender keeps the original detail levels before subdividing, so that you can use those for the more distant LOD levels.