I mostly deal in deeds so I'm not well-versed in certificates. 

With an elevation certificate flood is actually not very expensive. 

Make sure you get all relevant documents prior to close including move in pictures, catalog, tenant applications, contact information, rental certificates, and maintenance records. 

You can only STR certain unit types, you can only rent "36 contracts per year", you need a $900+ per year certificate, town taxes, they require someone to meet your guest at checkin, on and on.

I'd give the prospective tenant a choice, 1. one month longer than projected completion and they must vacate on that date because you will be finding a new tenant 30 days before they leave or 2. two month's extra and if there are delays for any reason you will allow them to remain until the house has a certificate of occupancy. 

- I have considered getting another job, but with everything going on at work (Currently getting a certification) the free time I do have, I want to spend learning and building my RE business.2.)

I did find quite a few articles stating that certifications don’t seem to matter.

Is there a need to re-certify and get a certificate of occupancy?

@Leon Lai: one thing that adds to the cost of window replacement in Michigan, is the state requirement that any working area bigger than 6 square feet, requires a contractor to have a state issued Lead-Based Paint (LBP) certificate, showing they passed a class on how to address LBP while working on houses.While that requirement excludes a lot of handyman, $1000/window is still abnormally high.I would question your PM as to why, "her findings are only a couple of contractors".

If you want to take it a step further, then you can ask the seller to have the tenants provide estoppel certificates.