Is it sufficient to keep a "pass" grade in the course, or will the bar for achieving the MicroMasters program be higher than merely pass?

The passing grade for each course is independent of the MicroMasters program credential. A pass is a pass. The specific grade is set by the instructor and is usually 60% to pass. When applying to the MIT graduate program, we will use the actual scores in the admissions process – but that is independent of earning the MicroMasters program credential.