This will affect your NOI and therefore reduce your maximum LTV. 

B. what happens when you inject more funds into the principal: does the end date of the loan reduced, or does the monthly payment go down?

Having the license is super beneficial because you can earn additional income from helping friends/family and also convert non wholesale deals to listings if the seller isn't motivated enough. 

The tax benefits from doing this should help reduce or even eliminate capital gains and depreciation recapture upon sale, but again you need competent advisors to set everything up to get the optimal benefits from this strategy. 

By May 2019, I expect the building to be 100% rehabbed earning an NOI of $55,200 with a Cash Flow of about $1,600 per month (after PITI, Vacancy, CAPEX, etc.) and a CoC Return of 57%!

I believe the RE investors will not need to take a reduced profit for an increased expenditure that is likely to impact such a large percentage of the market investors. 

I know there are a lot of benefits to opening a business, and that I have a 2-year window before making any actual earnings that I can still get the benefits of write-offs (vehicle, office, repairs, etc.).

The goal of those things is to get you there, get you excited, and get you to sign up for a 3-day "training" that is reduced to such a ridiculously low price during the "free" presentation so that you feel stupid if you turn it down.At that 3-day training, you get more hype, albeit in greater detail, to give you more hope and get you excited enough to sign up for one of their "in-depth" training programs that range anywhere from $15,000 up to $50,000. 

The state of MI has a grant that would cover 50% of the upstairs reno reducing our reno price to ~300k.

Realtor wants you to carry the note, AND expects to earn double commission?