A cookie cutter first deal looks like:Purchase: 65k - 90kRehab: 50k - 75kARV = Project Cost/.7Neighborhood: B or betterRehab type: cosmeticAvg Days on Market in zip code: 30 or lessThat's an example of a very safe deal for a lender to fund for a newbie.For a 0 experience expect to pay 11.5%+ in interest.Keep in mind the cost of a project's lifecycle. 

I used to do junk removal and demolition for these kinds of companies and saw all the worst case scenarios in columbus from tenants that can pay $800 per month. check the vetting requirements, raise the price to get into your unit. 900 per month is cheap in columbus if you are buying c class make sure to take a little more like 2 months rent so the people moving in aren't scraping by

For the full appraised value or just enough to pay back the small note+renovation costs?  

If you're going to manage a GC, make sure to meet them in person and avoid paying for the entire job upfront (typically for smaller jobs, you will pay half upfront, and half at the end). 

This includes keeping detailed records of all transactions.Mortgage Payments:Handling Income: The LLC can pay the rent for the use of the rental space, which I can then use to help pay off the mortgage.

If not, simply park your money into funds or stuff like that.

Someone agreed to pay and not only didn't but refused to leave a property they are not paying for so yea I guess your right that is fraud in my opinion. 

Is it a “bad” decision to put 20% down on this multiplex, likely have most of the mortgage covered by the rental income while continuing to pay rent at my current apartment? 

I would pay the 2500 but I dont trust the seller to get the place to pass.

I also had non-paying tenants that owed me, HVAC unit needing replacement, large trees hanging over property structure that suddenly died due to beatle infestation and college tuition due all at the same time.