It helps to be familiar with vendors too, my rule, ignore small unknown sources for maintenance receipts/charges as many play games, larger reputable companies will have more standardized pricing.If you can determine vacancies from lease files, good, but still be careful for leases that can't be verified by lease receipts/deposits.

LTV is 75%. 5 PlexTotal Rents: $45,600Vacancy 8.7%: $3,967Taxes: $4,520Insurance: $2,100PMC: $4,560Repairs: Unknown (Could be $1,000 or best guess of 10% of GRI $4,560) Need inspectorElectricity, Heat & Water: $2,500Misc.: $200Total Expenses: $14,880NOI: $26,753Mortgage: 4.63% Debt Service: $18,026Cash Flow: $8,727Down Payment: $97,500CoC if Maintenance at $1,000: 8.9%CoC if Maintenance at $4,560: 5.3%The maintenance portion of the above is not fully vetted and could bring my CoC return lower.

Go to settings > Calls > Uncheck "Ask unknown callers to say their name"

The fear of the unknown has always  allowed my subconscious to dial down the volume of that little voice. 

My advice is to try to make sure you have a bit of cash set aside for unknowns.

I don't see why they would recommend to invest their clients funds in an unknown area like notes.

But I'll do the best I can to help from reading what you posted based on price it seems good but there's still a lot of unknowns, since your house hacking and it's a duplex this might be common sense but please check if you ever decide to sell the property would it be sold as one collective property for 150k or separate I mention this because it seems like you'll be using a hard money lender.Also when it comes to rehab if you don't feel comfortable estimating the rehab do what I have done contact several rehabbers and show them the property and get a quote estimate that way.Along with this to eliminate any doubt the most important information (depending on your exit strategy) is the ARV you generally get this information from realtors to see what similar properties have sold and how long does a similar property take to sell.

If it turned out we couldn't fix it (we were on our last attempt, actually, before giving up and making the call), we would have called an expert in, feeling more comfortable at that point that it would be worth the unknown but likely expensive cost.   

Well my mistake was that this was a $258,000 home and the closing cost for it was $5,000 and I for some unknown reason thought it was $3,000.

Then you should factor your security deposits and several other unknowns in you purchase price.