What counts as 'interesting' or related to medicine?
Play out the following scenarios for me.
interning at the World Health Organization for 1 year
management consulting at McKinsey for 1-2 years
working for a health care startup for 1-2 years
founding a clinic / hospital in Kenya for 1-2 years
I think all of those, with the exception of McKinsey, would qualify as being at least peripherally related to medicine.
As for interesting, well that is in the eye of the beholder. Some programs don't really care what you do with your time off, others prefer you do something clinically oriented to keep your skills up and others just like to see you weren't laying on your mother's couch for 7 months.
Also, what are the criteria for repeating intern year or not? Why does it seem so nebulous and not more cut and dry?
It seems nebulous because it is. There are no hard and fast rules about this. Some programs require anyone out a certain length of time to repeat the year (in almost all cases it would be more than 2 years away from medicine), others do not. Its judged on a case by case basis.
Accept that you may have to repeat your intern year, especially if you do something non-clinical and that there are no answers to these questions.
What is the 7 year time limit?
You have 7 years (unless in an MD/PhD program) to pass all 3 USMLE steps. The clock starts ticking when you first take Step 1.
Again, under what circumstances do you have to repeat it?
Again, there are no hard and fast rules. Some programs will make you repeat if your intern year was significantly different from what they offer, if it was sufficiently long ago, if you have been out of clinical medicine, etc. There is no one answer to this question except to say that if you do not complete your intern year, fail to meet requirements set by your specialty board or do so in poor standing, then you will always have to repeat it.
What implications does it have for the licensing board? Are you seriously saying it would cause a problem? In this case, is leaving before or after doing an intern year worse, or does it matter?
Any time away from training after graduation from medical school must be accounted for and proof of your activities must be provided when you apply for a license, for a job, for hospital credentials/privileges. It is generally not a problem, only a PITA, unless you cannot account for your time or if you are licensed and let it lapse.