Nobody is really going to look that closely. This isn't undergrad, the number of "research hours" you list doesn't matter--obviously the amount of time you can spend on research would vary wildly depending on what stage of school you're in. What matters is the quality of the research, your personal involvement, and if you have any deliverables (posters/presentations/pubs). So unless it is very straightforward to answer those questions, I think they are left as optional for a reason and would not exert any significant effort to coming up with an answer for them.
I would have some ballpark estimate in mind of how much time you spent doing "research" in case you're asked, but that really is just an asinine question at the residency interview stage, IMO.