During session runs, the files created are namely Errors log, Bad file, Workflow low and session log.
Throughput option can be found in informatica in workflow monitor. In workflow monitor, right click on session, then click on get run properties and under source/target statistics we can find throughput option.
Reusable transformation is used numerous times in mapping. It is different from other mappings which use the transformation since it is stored as a metadata. The transformations will be nullified in the mappings whenever any change in the reusable transformation is made.