Hi Ken
Your information seems to be fairly correct. As this is new legislation and has not been implemented yet, there are still a lot of unknowns.
You are correct that government has changed the definition of short-term to anything under 90 days; whereas, it is currently anything under 30 days. A lot of visiting professionals, executives, students, nurses and doctors will be faced with the very same challenge.
As far as I know, the government has not yet begun their registration numbering system. Also, to my understanding, those that live in their principal residence and have a separate suite may continue to rent out short-term stays, as long as they register (when that system comes online).
Here is a link to the BC gov website, which may provide some additional answers for you.
https://www2.gov.bc.ca/gov/content/housing-tenancy/short-term-rentals
To my understanding, I think, stays of 90 days or longer will not be subject to the new rules.
Good luck.