Thanks!
Well, for starters, 2099 is a grad course which has an advanced undergraduate or graduate course as a prerequisite. If you are a current Harvard student, other Harvard students or the Q guide should be your first step. If you are not yet a Harvard student, the question is premature.
Ec 1057 seems like a relatively lightweight course, perhaps directed at a wide audience. There may not be much Q-guide information because both instructors are visiting lecturers. Ec 2099, on the other hand, is taught by Scott Kominers. That guy finished his PhD thesis at Harvard in 2 years after undergrad (also at Harvard). It won’t be an easy course, for sure.