Maximum number of jobs per project...

[ray.wurlod]

Your understanding is incorrect. SC in this case is "source code" - it contains the C++ source generated by compiling Transformer stages, it may contain C++ code from Build stages, it contains the compiled versions thereof, and it contains osh scripts that are interludes to them.

There's no such thing as "integrated with" QualityStage. The tool is the DataStage and QualityStage Designer. RT_QSnnn is created for any job that includes a Data Quality stage type.

DS_TEMPnnn is always created. Among other things, it is used for intermediate saves from Designer, for example when you click OK to save changes in a Transformer stage, you may or may not end up saving the job design itself. So the intermediate changes can be kept in DS_TEMPnnn.