auto triangulation occurs at run time when the model is loaded afaik,
max auto triangulates everything in poly :-p go to the display panel and turn off 'edges only' they just aren't visible edges
if the export format needs tris it will force to these hidden edges, if it allows >3 edges it will export the shape that way, however there is no guarantee that the exporter won't flip your hidden edges in all weird ways. I also know that some mesh algorithms really really hate non-tri meshes (picking especially), I don't know if SCP implements these, but if it does, it will have issues if it doesn't auto triangulate on load.
Now I am especially curious about how the move to full GLSL shaders will effect the poly throughput performance. This essentially removes any overhead in the engine for textures and pretty much moves everything to the hardware pipeline. What this gains is the ability to significantly ratchet up the texture data (basically let the video card -> memory transfer be the limiting factor, not some weird caching and swapping in the engine) but it will mean that every light will be per pixel. All of the meshes will have to be exported with binormals and more mesh detail will mean a lot more normal lookups.
I'm also concerned about closed meshes on detail meshes (backfaces filled), this would seem to create a culling and occlusion nightmare for the card, most other games either force closed meshes(best option for engine, pain for artists as each lod has to be a unique closed mesh, and textures almost always have to be baked from the higher lod) or approach it with aggressive lodding and layered meshes. (have to be careful to avoid Z buffer issues and how shaders use the geometry)