RE: [V8i MicroStationAPI] ElementFacetSet

A couple comments that may be of some help.

WRT #1.  The MDL example "imodelvisitor" has a method that may be of help called: Reporter::ReportFacetSet.  A few key lines are:

imodelvisitor\Reporter.cpp:843:    int pCount = pFacets->GetPointCount();
imodelvisitor\Reporter.cpp:844:    int fCount = pFacets->GetPointIndexCount();
imodelvisitor\Reporter.cpp:852:        ReportDpoint3d (L"Facet_Point",*pFacets->GetPoint(i),loopNodeP,Adjustment_None);
imodelvisitor\Reporter.cpp:855:    const Int32 * pFacetIndex = pFacets->GetPointIndices();

WRT #4

When implementing an IElementGraphicsProcessor consider the two output options for _ProduceGPAs and _ProduceFacets, taking careful note of the "param comments" of each:

struct  IElementGraphicsProcessor
{
//! Allow open curves, closed curves, and regions to be output as a GPArray. Necessary for collecting
//! higher level graphics such as complex strings, complex shapes, and regions.
//! @param[in] isCurved Graphics output would contain non-linear geometry.
//! @note When returning true you also need to implement _ProcessGPA.
virtual bool        _ProduceGPAs (bool isCurved) const {return true;}

//! Allow surface and solid geometry to be output as a facet set. 
//! @param[in] isIndexedPoly Output will be from a call to AddIndexPolys, ex. mesh element.
//! @return true to output facets for surface and solid geometry.
//! @note When returning true you also need to implement _ProcessFacets.
virtual bool        _ProduceFacets (bool isIndexedPoly) const {return isIndexedPoly;}

FYI.  Imodelvisitor sample also has some code for working with GPAs here:  imodelvisitor\Reporter.cpp:872:void  Reporter::ReportGPArray

HTH,
Bob