Does anyone fear crashing and burning at some point if something unforeseen happened such as 2008? 

It's unfortunate, but as soon as a tenant thinks that you'll "be cool about it" if something unforeseen happens, things suddenly start to come up more frequently.

I read that Subject-to completion appraisals have to be written because something unforeseen prevented the completion of the project.

The renovation costs may include a contingency reserve and renovation-related costs.Contingency Reserves: Contingency reserves 10 % required for any unforeseen cost overruns that may occur during construction.Unused contingency reserves that were financed into the loan will be applied to the principal balance of the loan.

However, if in doing the inspections / contractors come back with some unforeseen hidden HUGE cost you could back out of the purchase. 

By 2025, I want to earn at least $4,000 net profit per month from rental income.The idea is to buy my first MFH with an owner occupancy loan, live in it for a year, rent out the other unit, then after a year I'd rent out my unit and buy another duplex or triplex.With my $3,100 monthly net cash flow right now, I will have $18,600 in cash every 6-months (barring any unforeseen expenses).

The renovation costs may include a contingency reserve and renovation-related costs.Contingency Reserves: Contingency reserves 10 % required for any unforeseen cost overruns that may occur during construction.Unused contingency reserves that were financed into the loan will be applied to the principal balance of the loan.

If you are selling for health, work, unforeseen circumstances, you might qualify. 

for me I take the stance if your landlord and cannot afford to get rent for a month or two through what is a situation that was or Is unforeseen and your tenant is not causing it.. then your an under capitalized landlord .. so there is the counter point to all these people that say evict the tenant.. 

.$5K(2K metal roof sheathing, $2k septic chamber, $1K unforeseen issues)Purchase price $335,000(all 3 properties included)So what do you think B.P.community, is this a good deal?